Articles containing PTFE having improved dimensional stability particularly over long lengths, methods for making such articles, and cable/wire assemblies containing such articles

ABSTRACT

The present disclosure relates to methods of making an article comprising PTFE, methods of making expanded articles comprising PTFE, articles comprising PTFE, and expanded articles comprising PTFE having improved mechanical and electrical performance and particularly reduced variability in mechanical, electrical and dimensional properties, particularly over long lengths.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119(e) to U.S. PatentApplication No. 61/901,923 entitled “ARTICLES CONTAINING PTFE HAVINGIMPROVED DIMENSIONAL STABILITY PARTICULARLY OVER LONG LENGTHS, METHODSFOR MAKING SUCH ARTICLES, AND CABLE/WIRE ASSEMBLIES CONTAINING SUCHARTICLES,” by McCoy et al., filed Nov. 8, 2013, which is assigned to thecurrent assignee hereof and incorporated herein by reference in itsentirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to paste extruded articles comprisingPTFE, such as a PTFE film or tape, methods for making such articles, andproducts such as wire or cable assemblies having such articles.

RELATED ART

Unsintered paste extruded polytetrafluoroethylene (PTFE) articles, suchas films and tapes, are used in many applications including sealingjoints, insulating conductive wires, and protecting materials fromcorrosive elements. PTFE demonstrates good chemical and heat resistance,and electrical insulation characteristics, as well as a low coefficientof friction. However, in general, paste extruded PTFE articles can haveless than desirable mechanical properties. In particular, currentprocesses for manufacturing paste extruded PTFE articles are unable tomaintain dimensional parameters, mechanical properties, porosity, andother characteristics within necessary tolerances, and especially overlong lengths.

In general, paste extruded PTFE articles are produced in a pasteextrusion process where to generate long lengths of monolithic PTFEarticles, successive preforms (compacted PTFE mixtures) having a mass ofabout 3 lbs of PTFE are paste extruded. The use of successive preformsresults in a joint or seam where the successive preforms meet. Thisjoint or seam can be distinctly identified in the final monolithic PTFEarticle. When long lengths of monolithic PTFE articles are needed, suchas in the order of 300 meters or greater, traditional processes cangenerate 4 or 5 seams over such lengths, depending on the thickness andwidth of the PTFE article. The joints or seams have undesirableproperties of the PTFE article such as undesirable dimensionalparameters, mechanical properties, electrical properties, porosity, andother characteristics. In particular, the variation of these propertiesacross the entire length of the monolithic PTFE article can be high,particularly due to the presences of these joints.

The variation in these properties is undesirable for many reasons. Forexample, during winding of the PTFE article onto a cable or wire, a weakpoint, particularly at the joint, having a mechanical strength outsideof tolerance can cause breakage of the tape. Moreover, in such cable orwire assemblies, insulative properties, such as the dielectric constant,need to be maintained above a target value. The low spots, particularlycreated at the joint, lead to reduced electrical performance. A largeamount of effort has been placed on making the preform joints asseamless as possible, but it has not heretofore been possible toeliminate the large variation in properties and distinct presence of ajoint and its associated drawbacks.

CN202711884, a Chinese utility model application, describes a PTFE filmfor a power cable with extremely broad ranges of lengths and thicknesstolerances. However, CN202711884 does not disclose or suggest how toachieve such thickness tolerances, and includes no examples. In fact,the only disclosure within CN202711884 on how to make the PTFE tapedescribed is a simplistic germane overview of all PTFE paste extrusiontechniques. Moreover, CN202711884 is completely devoid of any teachingto reduce or eliminate joints or seams over long lengths or in achievinglow variation of other properties. At the time of the filing of thisapplication, all known methods of forming long lengths of monolithicarticles required successive paste extrusion of small preforms (about 3lbs of PTFE).

As such, a considerable need exists, particularly in the aerospaceindustry, for wire and cable insulation in the form of a PTFE articlethat has a low variation in properties such as dimensional parameters,mechanical properties, electrical properties, porosity, and others overa long length of monolithic article.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated by way of example and are not limited in theaccompanying figures.

FIG. 1 illustrates a schematic process flow diagram of a method ofmaking a PTFE article according to an embodiment.

FIG. 2 illustrates a schematic representation of a preform tubeaccording to an embodiment.

FIG. 3 illustrates a cross-section of a preform tube according to anembodiment.

FIG. 4A illustrates an exploded view of a container assembly forincubating a PTFE and lubricant mixture according to an embodiment.

FIG. 4B illustrates a section view of an assembled container assemblyfor incubating a PTFE and lubricant mixture according to an embodiment.

FIG. 5 illustrates a section view of a loaded preform tube prior tocompaction according to an embodiment.

FIG. 6 illustrates a section view of a loaded preform tube duringcompaction according to an embodiment.

FIG. 7 illustrates a section view of a loaded preform tube duringcompaction according to an embodiment.

FIG. 8 illustrates a section view of a translation and extrusionapparatus during translation into communication with an extrusion dieafter compaction according to an embodiment.

FIG. 9 illustrates a section view of a translation and extrusionapparatus after translation and in communication with an extrusion dieaccording to an embodiment.

FIG. 10 illustrates a close up view of the interface between a compactedmixture and the extrusion die after translation according to anembodiment.

FIG. 11A illustrates a section view of a translation and extrusionapparatus showing simultaneous extrusion and compaction according to anembodiment.

FIG. 11B illustrates a section view of an extrusion die according to anembodiment.

FIG. 12A illustrates a perspective view of a segment of PTFE articleaccording to an embodiment.

FIG. 12B illustrates a perspective view of a segment of expanded PTFEarticle according to an embodiment.

FIG. 13 illustrates a cross-section of a cable assembly according to anembodiment.

FIG. 14 illustrates a cross-section of a cable assembly according toanother embodiment.

FIG. 15 illustrates a break away perspective view of a cable assemblyaccording to another embodiment.

FIG. 16 illustrates a plot showing the improvement in lubricantconcentration during mixing according to an embodiment.

FIG. 17 illustrates a plot showing the improvement in lubricantconcentration during mixing according to an embodiment.

FIG. 18 illustrates a plot showing the lubricant concentrationdeviations after incubation without a barrier structure.

FIG. 19 illustrates a plot showing the lubricant concentrationdeviations after incubation with a barrier structure according to anembodiment.

FIG. 20 illustrates a plot showing the cross direction tensile stressperformance of a PTFE article according to an embodiment compared to astandard PTFE article.

FIG. 21 illustrates a plot showing the cross direction tensile stressperformance of a PTFE article according to another embodiment comparedto a standard PTFE article.

FIG. 22 illustrates a plot showing the thickness deviation of a PTFEarticle according to an embodiment.

FIG. 23 illustrates a plot showing the thickness deviation of a PTFEarticle according to another embodiment.

FIG. 24 illustrates a plot showing the thickness deviation of a standardPTFE article.

FIG. 25 illustrates a plot showing the machine direction tensilestrength at max load of an expanded PTFE article according to anembodiment compared to a standard PTFE article.

FIG. 26 illustrates a plot showing the machine direction tensilestrength at manual break of an expanded PTFE article according to anembodiment compared to a standard expanded PTFE article.

FIG. 27 illustrates a plot showing the cross direction tensile strengthat max load of an expanded PTFE article according to an embodimentcompared to a standard expanded PTFE article.

FIG. 28 illustrates a plot showing the specific gravity of an expandedPTFE article according to an embodiment compared to a standard expandedPTFE article.

FIG. 29 illustrates a plot showing the machine direction tensilestrength at various positions across the length of an expanded PTFEarticle according to an embodiment.

FIG. 30 illustrates a plot showing the machine direction elongation atvarious positions across the length of an expanded PTFE articleaccording to an embodiment.

FIG. 31 illustrates a plot showing the specific gravity at variouspositions across the length of an expanded PTFE article according to anembodiment.

FIG. 32 illustrates a plot showing the thickness at various positionsacross the length of an expanded PTFE article according to anembodiment.

Skilled artisans appreciate that elements in the figures are illustratedfor simplicity and clarity and have not necessarily been drawn to scale.For example, the dimensions of some of the elements in the figures maybe exaggerated relative to other elements to help to improveunderstanding of embodiments of the invention.

DETAILED DESCRIPTION

The following description in combination with the figures is provided toassist in understanding the teachings disclosed herein. The followingdiscussion will focus on specific implementations and embodiments of theteachings. This focus is provided to assist in describing the teachingsand should not be interpreted as a limitation on the scope orapplicability of the teachings. However, other embodiments can be usedbased on the teachings as disclosed in this application.

The terms “comprises,” “comprising,” “includes,” “including,” “has,”“having” or any other variation thereof, are intended to cover anon-exclusive inclusion. For example, a method, article, or apparatusthat comprises a list of features is not necessarily limited only tothose features but may include other features not expressly listed orinherent to such method, article, or apparatus. Further, unlessexpressly stated to the contrary, “or” refers to an inclusive-or and notto an exclusive-or. For example, a condition A or B is satisfied by anyone of the following: A is true (or present) and B is false (or notpresent), A is false (or not present) and B is true (or present), andboth A and B are true (or present).

Also, the use of “a” or “an” is employed to describe elements andcomponents described herein. This is done merely for convenience and togive a general sense of the scope of the invention. This descriptionshould be read to include one, at least one, or the singular as alsoincluding the plural, or vice versa, unless it is clear that it is meantotherwise. For example, when a single item is described herein, morethan one item may be used in place of a single item. Similarly, wheremore than one item is described herein, a single item may be substitutedfor that more than one item.

As used herein, the term “joint” or “seam” refers to a perceptibleregion in a paste extruded PTFE article which is an artifact of thepaste extrusion of successive preforms.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. The materials, methods, andexamples are illustrative only and not intended to be limiting. To theextent not described herein, many details regarding specific materialsand processing acts are conventional and may be found in textbooks andother sources within polymer, and particularly paste extruded PTFE arts.

In general, the present disclosure describes methods of making PTFEarticles, PTFE articles, expanded PTFE articles, and cable assembliescontaining such PTFE articles. The PTFE articles have improveddimensional, mechanical, and electrical properties, and in particular,consistency of these properties over long lengths. In certainembodiments, unique methods for making such PTFE articles can includeusing significantly larger preforms and/or steps to be able to mix,handle, compact, and paste extrude such significantly larger preforms,particularly in a semi-continuous process. The concepts are betterunderstood in view of the embodiments described below that illustrateand do not limit the scope of the present invention.

Referring initially to FIG. 1, there is illustrated a general schematicdiagram for a method and system 10 for forming a paste extruded PTFEarticle according to one embodiment. In general, one method of forming aPTFE article described herein can include providing raw materialsincluding PTFE and a lubricant; mixing the raw materials to uniformlydisperse the components to form a mixture or paste 20; loading themixture into a preform 30; compacting the mixture 40; translating thepreform into communication with a die 50; extruding the mixture to forma tape 60; calendering the article 70; drying the article 80; andwinding the article into a roll 90. It is to be understood that specificembodiments described herein can include less than all of the stepsdescribed above or can include other additional steps as is customary inthe art.

Initially, raw materials can be provided into a mixing apparatus, andthe materials can be thoroughly mixed.

The raw materials can include a non-meltprocessable polymer. Forexample, non-meltprocessable polymers can include liquid crystalpolymers (LCP), certain fluoropolymers such as perfluoropolymers, and inparticular polytetrafluoroethylene (PTFE), modifiedpolytetrafluoroethylene (m-PTFE), or combinations thereof. In particularembodiments, the raw material includes polytetrafluoroethylene (PTFE),and can even consist essentially of PTFE. As used herein, a raw materialmixture which consist essentially of PTFE refers to a raw materialmixture that includes PTFE, a lubricant, and any other useful additive.Although the remainder of the disclosure will refer to PTFE, it is to beunderstood that other non-meltprocessable polymers, such as liquidcrystal polymers, may be used in addition to or as an alternative toPTFE. It is further understood that the use of the word “PTFE” hereinrefers to any type of PTFE material or any mixture containing a PTFEbased material.

The PTFE raw material can be in particulate form. In certainembodiments, the PTFE particulate can have an average particle size(D₅₀) of no greater than 50 microns, no greater than 20 microns, or evenno greater than 1 micron. In further embodiments, the PTFE particulatecan have an average particle size of at least 0.01 microns, at least0.05 microns, or even at least 0.1 microns. In particular embodiments,the PTFE particulate can have an average particle size in a range of anyof the minimum and maximum values described above, such as in a range of0.05 microns to 20 microns, or even 0.1 microns to 1 micron.

The raw materials can further include a lubricant, which after mixingwith the PTFE particulate can form a slurry or paste such that themixture can be paste extruded. The lubricant is driven off duringdrying, and advantageously, the finished product is essentially free ofthe lubricant material.

Examples of suitable lubricants can include a hydrocarbon-based liquid,such as the isoparaffinic solvents sold under the Isopar tradename bythe ExxonMobil Chemical Co. Particular lubricants can include Isopar H,Isopar K, Isopar M, Isopar G, or combinations thereof.

In certain embodiments, the raw material mixture can include the PTFEparticulate in an amount of at least 40 wt. %, at least 60 wt. %, atleast 78 wt. %, or even at least 80% based on the total weight of thePTFE and lubricant. Further, the raw material mixture can include thePTFE particulate in an amount of no greater than 95 wt. %, no greaterthan 90 wt. %, or even no greater than 88 wt. %, based on the totalweight of the PTFE and lubricant. In particular embodiments, the rawmaterial mixture can include the PTFE particulate in an amount in arange of any of the minimum and maximum values described above, such asin a range of 60 wt. % to 95 wt. %, 75 wt. % to 90 wt. %, or even 78 wt.% to 88 wt. % by weight, based on the total weight of the PTFE andlubricant.

The raw material mixture can include a ratio of PTFE to lubricant of atleast 1, at least 2, at least 3, at least 4, or even at least 5.Further, the raw material mixture can include a ratio of PTFE tolubricant of no greater than 15, no greater than 11, or even no greaterthan 9. In particular embodiments, the raw material mixture can includea ratio of PTFE to lubricant in a range of any of the minimum andmaximum values described above, such as in a range of 2 to 11 or even 5to 9.

The raw material mixture can further include any useful additives intheir useful amounts as understood by those skilled in the art. Examplesof additives include, but are not limited to photosensitive materials,fillers, processing aids, pigments, and combinations thereof. Certainadditives may remain in the final product, while other additives may bedriven off with the lubricant.

Particular additives useful in certain embodiments can includephotosensitive materials and additives to enhance the photosensitivematerial, which can make a PTFE article laser markable. Thephotosensitive material can be an organic compound. In certainembodiments, the photosensitive material can contain an oxide, such asSnO₂, ZnO, AZO, TiO₂, CeO₂, Nb₂O₅, MoO₃, WO₃, V₂O₅, Cr₂O₃, Fe₂O₃, NiO,CuO, CdO and Tl₂O₃ or combinations thereof. When present, thephotosensitive material can be present in the raw material mixture in anamount of at least about 0.1%, at least about 0.5%, or even at leastabout 1% by weight, based on the total weight of the PTFE andphotosensitive material. Further, the photosensitive material can bepresent in the raw material mixture in an amount of no greater than 20%,no greater than 10%, or even no greater than about 5% by weight based onthe total weight of the PTFE and photosensitive material. In particularembodiments, the photosensitive material can be present in the rawmaterial mixture in a range of any of the minimum and maximum valuesdescribed above, such as in a range of 0.1% to 20%, 0.5% to 10%, or even1% to 5% by weight, based on the total weight of the PTFE andphotosensitive material. It is further understood that thephotosensitive material desirably remains in the final product. Furtheradditives that can enhance the photosensitive material and can even be aphotosensitive material themselves can include materials such as zincsulfide and organic synergists, such as polyimide, that can enhancecontrast ratio.

In certain embodiments, the total amount of the raw material mixture tobe loaded into a single large preform tube can be mixed in a singlebatch. A particular advantage of certain embodiments of the presentdisclosure is the discovery of the improvement in the properties of thefinal PTFE article by mixing the total amount of the raw materialmixture to be loaded into a single large preform tube, particularly whendealing with the large preforms described in more detail below. Intypical paste extrusion techniques, small batches of raw material (about3 lbs. of PTFE) were mixed and loaded into small preform tubes. In thelarger preforms of the current disclosure, the inventors discovered thatmixing a single large batch for each preform can provide significantlylower concentration variances and inconsistencies throughout the lengthof the preform than using multiple small batches that were independentlymixed and combined in a preform tube. These improvements were realized,in part, as decreased total thickness variation in the final PTFEarticle and other improvements in the PTFE article's mechanical andelectrical properties as described in more detail below.

As used herein, the phrase “preform tube” refers to the vessel fromwhich the compacted raw material mixture is paste extruded. As usedherein, the word “preform” refers to actual raw material mixture withinthe preform tube. As used herein, “preform” is synonymous with thephrases “raw material mixture” or “compressed raw material mixture.”

While, the inventors discovered that by mixing a single batch of theentire amount of raw materials that was to be loaded in a single preformtube aided in reducing the total thickness variation of the extrudedarticle, it was also discovered that increasing the amount of the rawmaterial mixture (i.e. increasing the preform and preform tube size)resulted in extreme difficulty in obtaining a homogeneous mixture withlow variability in lubricant concentration throughout the large mixture.For example, the inventors discovered that traditionally used mixingmethods and equipment were not capable of providing consistenthomogeneously mixed batches of the size described below. In other words,significant lubricant load variation within and between these largebatches was discovered, and further improvements were needed in mixingin a large single batch.

Accordingly, the current inventors had to significantly modify themethods and apparatuses used to mix the large batches to obtainconsistent homogeneous mixtures to form the large preforms discussedherein. For example, particular modifications can include improving theconsistency and accuracy of the amount of lubricant to PTFE; improvingthe spray patterns for lubricant addition; and modifying the preformstructure.

Regarding improving the consistency and accuracy of the amount oflubricant to PTFE within the mixture, in certain embodiments, steps caninclude providing a mixer and loading the mixer with the desired amountof PTFE. Steps can further include weighing a container loaded withlubricant. Steps can further include while the loaded container is beingactively and continuously weighed, the lubricant can be added to themixer with PTFE. A controller can be in communication with the weighingdevice and the lubricant dispensing apparatus. The controller can beconfigured to stop dispensing lubricant once a desired amount oflubricant (measured by weight) has been added to the mixture and removedfrom the container being weighed. As such, a consistent and exact amountof lubricant can be added to a batch of PTFE resin. It is reiteratedthat in smaller preforms that were traditionally used, the variation inlubricant loading consistency and accuracy was not recognized as aproblem that would significantly effect the properties of the formedPTFE article.

Regarding improving the spray patterns for lubricant addition, theinventors discovered that the lubricant spray configuration into themixing apparatus has a strong relationship to the mix time and mixuniformity. Previously used mixing apparatuses for PTFE article pasteextrusion relied on a single spray tip. The inventors discovered thatusing more than one spray tip, such as 2 spray tips, allowed for fineratomization and faster addition of the lubricant, which was discoveredto aid in achieving consistent homogeneous mixtures, in particular forthe size of preforms discussed below.

In embodiments described herein, mixing can include mixing all of theraw materials to be loaded in a single preform tube in a single batch.Moreover, the single batch can contain at least 5 lbs, at least 7 lbs,at least 10 lbs, at least 12 lbs, at least 15 lbs, at least 17 lbs, atleast 20 lbs, at least 25 lbs, at least 30 lbs, at least 35 lbs, atleast 40 lbs, at least 45 lbs, at least 50 lbs, at least 55 lbs, atleast 60 lbs, at least 65 lbs, at least 70 lbs, at least 75 lbs, atleast 80 lbs, at least 85 lbs, at least 90 lbs, at least 95 lbs, or evenat least 100 lbs of the PTFE. Further, the single batch can contain nogreater than 500 lbs, no greater than 300 lbs, no greater than 200 lbs,or even no greater than 150 lbs of PTFE. In particular, the single batchcan contain a range of 5 lbs to 300 lbs of PTFE, 40 lbs to 200 lbs ofPTFE, or even 60 lbs to 150 lbs of PTFE.

Once a homogeneous mixture is obtained, the mixture can be stored andincubated in a container before being loaded into a preform tube. Afterincubation, the incubated mixture can be remixed prior to loading into apreform tube.

Referring now to FIGS. 4A-4B, the mixture can be stored and incubated ina container 201. The container assembly can include a container 201 anda support member 210. The support member can have any particular shape.In particular embodiments, and as illustrated in FIGS. 4A-4B, thesupport member 210 can have an outer profile 212 that generallycomplements the inner profile 214 of the container 201. Accordingly, incertain embodiments, the support member 210 can have a generallycircular shape, such as a disc shape. The support member 210 can becomposed of any suitable material(s). In particular embodiments, thesupport member 210 can include, and can even be substantially composed,of a polymer material. In very particular embodiments, the polymermaterial can include PVC.

The container assembly can further include a flexible sheet material220. The flexible sheet material 220 can be disposed below the supportmember, such as in between the support member 210 and the PTFE mixture230. The flexible sheet material 220 can include, and can even besubstantially composed, of a polymer material.

The raw material mixture can be incubated in the container assembly fora desired period of time to allow the lubricant to distribute throughoutthe resin, i.e. wick into the secondary particles. In certainembodiments, the raw material mixture can be incubated in the containerassembly for at least 12 hours, at least 24 hours, or even at least 36hours. In other embodiments, the raw material mixture can be incubatedin the container assembly for no greater than 84 hours, no greater than72 hours, or even no greater than 60 hours. In certain furtherembodiments, the raw material mixture can be incubated in the containerassembly in a range of any of the minimum and maximum values describedabove, such as in a range of 24-72 hours, or even 36-60 hours.

Another particular advantage of certain embodiments of the presentdisclosure is the ability to achieve a low variation in lubricantdistribution throughout the preform, and particularly in the largepreforms discussed herein. As discussed above, a consistent homogeneousmix in a large preform was not able to be obtained by traditionalmethods and equipment. It was surprisingly discovered that the inclusionof a support member and/or a flexible sheet after mixing and duringincubation with such large batches of raw material mixture discussedherein aided to reduce the loss of the lubricant to vapor space whichresulted in improving the ability to obtain consistent homogeneousmixtures when transferred to the preform tube and thereby improve thevariation in lubricant distribution in the preform, and provide improveddimensional, mechanical, and performance properties as discussed herein.

Referring now to FIG. 2, there is illustrated an example of a preformtube 200 for use in a PTFE paste extrusion process disclosed herein. Thepreform tube 200 can have a length P_(L) and a width P_(W). Inparticular embodiments, the length P_(L) of the preform tube 200 can begreater than the width P_(W).

In certain embodiments, the preform tube 200 can have a length of atleast 0.5 meters, at least 0.8 meters, at least 1 meter, at least 1.2meters, or even at least 1.3 meters. Further, the preform tube 200 canhave a length of no greater than 10 meters, no greater than 5 meters, nogreater than 3 meters, or even no greater than 2 meters. In particular,the preform tube 200 can have a length in a range of any of the minimumand maximum values described above, such as in a range of 0.5 meters to5 meters, 1 meter to 3 meters, or even 1.2 meters to 5 meters.

The preform tube 200 can have a width (also referred to as the diameterin a cylindrical preform) of at least 5 cm, at least 12 cm, or even atleast 14 cm. Further, the preform tube 200 can have a width of nogreater than 1,000 cm, no greater than 100 cm, no greater than 50 cm, oreven no greater than 30 cm. In particular, the preform tube 200 can havea width in a range of any of the minimum and maximum values describedabove, such as in a range of 5 cm to 100 cm, 12 cm to 50 cm, or even 14cm to 30 cm.

Referring now to FIG. 3, which illustrates a cross-section of thepreform tube of FIG. 2, along line A-A, the preform tube 200 can have across-sectional area of at least 100 cm², at least 140 cm², or even atleast 160 cm². Further, the preform tube can have a cross-sectional areaof no greater than 5000 cm², no greater than 1,000 cm², no greater than500 cm², no greater than 300 cm², or even no greater than 250 cm². Inparticular, the preform tube can have a cross-sectional area in a rangeof any of the minimum and maximum values described above, such as in arange of 100 cm² to 1,000 cm², 140 cm² to 300 cm² or even 160 cm² to 250cm².

The preform tube 200 can have a particular ratio of the length to thewidth. For example, the preform tube can have a ratio of the length tothe width of at least 3, at least 5, at least 7, at least 10, or even atleast 15. Further, the preform tube 200 can have a ratio of the lengthto the width of no greater than 100, no greater than 75, or even nogreater than 50. In particular, the preform tube can have a ratio of thelength to the width in a range of any of the minimum and maximum valuesdescribed above, such as in a range of 3 to 100, 5 to 75, or even 7 to50.

The preform tube 200 can have an interior volume, or capacity for a rawmaterial mixture, of at least 10,000 cm³, at least 15,000 cm³, at least20,000 cm³, or even at least 23,000 cm³. Further, the preform tube 200can have an interior volume of no greater than 100,000 cm³, no greaterthan 50,000 cm³, no greater than 40,000 cm³, or even no greater than30,000 cm³. In particular, the preform tube can have an interior volumein a range of any of the minimum and maximum values described above,such as in a range of 10,000 cm³ to 50,000 cm³, 15,000 cm³ to 40,000cm³, or even 20,000 cm³ to 40,000 cm³.

The preform tube 200 can be configured to hold a desired amount of acompressed raw material mixture as described above. For example, thepreform tube 200 can be configured to hold a raw material mixturecontaining at least 5 lbs, at least 7 lbs, at least 10 lbs, at least 12lbs, at least 15 lbs, at least 17 lbs, at least 20 lbs, at least 25 lbs,at least 30 lbs, at least 35 lbs, at least 40 lbs, at least 45 lbs, atleast 50 lbs, at least 55 lbs, at least 60 lbs, at least 65 lbs, atleast 70 lbs, at least 75 lbs, at least 80 lbs, at least 85 lbs, atleast 90 lbs, at least 95 lbs, or even at least 100 lbs of PTFE.Further, the preform tube can be configured to hold a raw materialmixture containing no greater than 500 lbs, no greater than 300 lbs, nogreater than 200 lbs, or even no greater than 150 lbs of PTFE. Inparticular, the preform tube can be configured to hold a raw materialmixture containing a range of 5 lbs to 300 lbs of PTFE, 40 lbs to 200lbs of PTFE, or even 60 lbs to 150 lbs of PTFE.

The preform tube can have any particular shape or profile, and inparticular embodiments can have a generally cylindrical shape asillustrated in FIGS. 2-3.

Similarly, the compressed raw material mixture in one batch (i.e.preform) formed in the preform tube can include at least 5 lbs, at least7 lbs, at least 10 lbs, at least 12 lbs, at least 15 lbs, at least 17lbs, at least 20 lbs, at least 25 lbs, at least 30 lbs, at least 35 lbs,at least 40 lbs, at least 45 lbs, at least 50 lbs, at least 55 lbs, atleast 60 lbs, at least 65 lbs, at least 70 lbs, at least 75 lbs, atleast 80 lbs, at least 85 lbs, at least 90 lbs, at least 95 lbs, or evenat least 100 lbs of PTFE. Further, the preform can include no greaterthan 500 lbs, no greater than 300 lbs, no greater than 200 lbs, or evenno greater than 150 lbs of PTFE. In particular, the preform can includea range of 5 lbs to 300 lbs of PTFE, 40 lbs to 200 lbs of PTFE, or even60 lbs to 150 lbs of PTFE.

Referring again to FIG. 1, methods of forming a PTFE article accordingto certain embodiments described herein can further include compactingthe raw material mixture that has been loaded into the preform tube.Compacting involves limiting the amount of volume that the raw materialoccupies, thereby reducing the void space between particles. Care shouldbe taken during compaction to maintain a substantially uniformdispersion of the PTFE and lubricant, which is difficult to control. Ifthe mixture is compressed too much, a portion of the lubricant can beforced or separated out of the mixture and can cause significantvariation in lubricant distribution throughout the preform. If themixture is compressed too little, the preform will fall out of thepreform tube during compaction or translation, and/or the mixture canseparate in the preform, causing lack of uniformity and resultingphysical and mechanical defects.

The inventors discovered that following traditional compactingprocedures associated with small preforms was ineffective whentransitioning to the larger preforms discussed herein. The inventorssurprisingly discovered a compaction method that allows for the pasteextrusion of such large preforms without the preforms falling out of thepreform tube. Moreover, the inventors surprisingly discovered thatcertain features in the compacting process can improve uniformity orhomogeneity of the large compacted mixture, which can result in improvedproperties such as total thickness variation and reduction of the sizeof the preform joint of the PTFE article.

Referring initially to FIG. 5, the preform tube 200 has a first end 300and a second end 310 opposite the first end 300. The first end 300 canbe arranged to be at a lower elevation than the second end 310. Forexample, the preform tube 200 can be in a generally verticalorientation, relative to a level surface. In other words, the preformtube 200 can be at an angle with a level surface such that force ofgravity acts on the raw material mixture 320 in the direction of thefirst end 300.

As illustrated in FIG. 6, in certain embodiments, compacting can includeactively compacting the mixture from the first end 300 and activelycompacting the mixture from the second end 310. As used herein, thephrase “actively compacting” refers to translational movement of a head,such as a piston head, toward the interior of the preform, therebydecreasing the void space between particles.

In certain embodiments, and as illustrated in FIG. 7, activelycompacting the mixture from the first end 300 can begin before activelycompacting the mixture 320 from the second end. For example, a firstpiston head 400 disposed adjacent to the first end 300 can be movedupward while the preform 200 and the second piston head 410 arestationary.

Further, in particular embodiments, actively compacting the mixture 320from the first end 300 can begin and be completed before activelycompacting the mixture 320 from the second end 310. In other embodiment,actively compacting the mixture 320 from the second end 310 can beginbefore actively compacting the mixture from the first end 300 has beenfully completed. Still further, in other embodiments, activelycompacting the mixture from the second end 310 can be completed beforeactively compacting the mixture from the first end 300 has been fullycompleted.

In yet still further embodiments, actively compacting the mixture fromthe first end 300 and actively compacting the mixture from the secondend 310 can occur, at least in part, concurrently.

It was surprisingly discovered that, for example, actively compactingthe mixture from the first end before actively compacting the mixturefrom the second end can allow for the large preform in the large preformtube to remain in a desired compacted state within the preform and not“fall out” during translation of the preform into communication with thedie as will be described in more detail below. As used herein, thephrase “fall out” or “falling out” refers to the preform coming out ofthe preform tube when not desired. Without wishing to be bound bytheory, the inventors discovered that by compacting from the first endbefore compacting from second end could allow for sufficient forceagainst the surface area of the interior of the vessel to keep themixture in a compacted state after opening of the first end and aid inpreventing fall out.

In certain embodiments, during active compaction, the compaction forceat the first and/or second end of the preform can be no greater than 500psi, no greater than 400 psi, no greater than 350 psi, no greater than300 psi, no greater than 280 psi, no greater than 270 psi, no greaterthan 250 psi, no greater than 240 psi, no greater than 230 psi, nogreater than 220 psi, no greater than 210 psi, no greater than 200 psi,no greater than 190 psi, or even no greater than 180 psi. Further,during active compaction, the compaction force at the first and/orsecond end of the preform can be at least 20 psi, at least 40 psi, atleast 60 psi, at least 80 psi, at least 100 psi, at least 120 psi, atleast 140 psi, or even at least 160 psi. In particular, during activecompaction, the compaction force at the first and/or second end of thepreform can be in a range of any of the minimum and maximum valuesdescribed above, such as in a range of 40 psi to 500 psi, 60 psi to 300psi, or even 80 psi to 250 psi.

In certain embodiments, the compaction force at the first end can beequivalent to or greater than the compaction force at the second end. Inother embodiments, the compaction force at the first end can beequivalent to or less than the compaction force at the second end. Inparticular embodiments, the compaction force at the first and secondends can be substantially the same. For example, the compaction force atthe first end can be within 50 psi, within 25 psi, or even within 10 psiof the compaction force at the second end.

Another particular advantage of the present disclosure is theachievement of the low compaction pressures described above and theresulting improvement in the dimensional stability and physicalproperties of the PTFE article formed using the compaction methoddescribed above. The raw material PTFE mixture is virtuallyincompressible. Thus, as the piston drives inward and compacts the PTFEand lubricant mixture, there is an exponential increase in thecompaction force. In traditional compaction of small preforms, theexponential increase during compaction to about 300 psi occurs virtuallyinstantaneously. The inventors surprisingly discovered that byincreasing the size of the preform (and the amount of mixture heldtherein) and using the compaction procedures as described herein, that aslower exponential rise in the applied compaction pressure occurs, andtherefore can be controlled, such that the compaction process can bestopped at lower compaction pressures. The inventors furthersurprisingly discovered that a lower compaction force, particularlylower than 300 psi or even lower than 280 psi, or still further lowerthan 220 psi resulted in a more uniform dispersion of the lubricant andPTFE, allowing for better control of properties such as total thicknessvariation. Moreover, the inventors surprisingly discovered that a lowercompaction force decreased the size (particularly the length wisedirection, and the overall mass) of a joint when extruding successivepreforms.

In further embodiments, the compaction speed, i.e. the speed the pistonhead travels during compaction can be at least 0.5 inches per second, atleast 0.75 inches per second, at least 1 inch per second, or even atleast 2 inches per second. In still further embodiments, the compactionspeed can be no greater than 20 inches per second, no greater than 10inches per second, no greater than 8 inches per second, or even nogreater than 5 inches per second. Moreover, the compaction speed can bein a range of any of the minimum and maximum values described above,such as in a range of 1 inch per second to 10 inches per second. It isfurther to be understood that the compaction speeds provided above canbe used for the first end and/or the second end.

In certain embodiments, the first end can be in a fully extend statewhile the raw material mixture is being added to the preform tube 200.This way, the distance the resin has to fall during loading can beminimized. Furthermore, during addition of the resin, the piston head atthe first end can be retracted to accommodate the raw material mixturethat is being added in the preform tube 200.

In further embodiments, after the compaction cycle has completed, andthe desired pressure has been reached, no further movement of the firstpiston head and/or the second piston head toward the compressed mixturecan occur. In other words, in certain embodiments, the compressedpreform may not be moved within the preform tube after compression andbefore placing the preform tube in communication with the die. It wassurprisingly discovered that any movement toward the compressed mixtureafter the compression cycle has been completed can result in the entiremixture from falling out of the preform tube during translation. As willbe discussed in more detail below, the first end can be open duringtranslation to enable fluid communication of the preform with the die.

Referring again to FIG. 1, the methods of forming a PTFE articledescribed herein can further include translating the preform intocommunication with the die 40.

Referring now to FIG. 8, which illustrates one embodiment of a set upfor translating preforms from a compaction step to a paste extrusionstep, during translation, the first end 300 of the preform tube 200 canbe open such that there is no physical member keeping the compactedmixture 320 from falling out. In other words, the compacted mixture 320can remain in a compacted state without being supported from the bottom.The first end 300 can be open during translation so that the preformtube 200 can be connected to the die 510 and in fluid communication withthe die 510 and thus push the compressed mixture through the die to bepaste extruded.

Referring again to FIG. 8, in certain embodiments, during translation, avacuum pressure 500 can be applied to the second end 310 to aid inholding the compacted mixture 320 within the preform tube 200. Referringto FIG. 9, once the first end 300 of the preform tube 200 is alignedwith the die 510 and in communication with the die 510, the vacuumpressure can be released. In certain embodiments, a positive pressure520 can be applied to the second end 320 to push the compressed PTFEmixture in the preform tube to move into the die 510, and optionallycontact a compressed PTFE mixture from the previous preform, whenpresent.

As further illustrated in FIG. 10, when the preform moves into the die,a pressure release structure 530 can be attached at the interfacebetween the preform tube 200 and the die 510 to allow trapped air orgases to be expelled such that the compressed PTFE mixture 320 can makeintimate contact with the remaining compressed PTFE mixture from theprevious preform 321, if present. It was surprisingly discovered thatthe release of the air at the interface during flow of the compactedmixture into the die can improve the dimensional and physicalproperties, and in particular, the variation of those properties in anextruded PTFE article.

Referring now to FIG. 11A, in certain embodiments, particularlyembodiments directed to semi-continuous paste extrusion of a PTFEarticle, translating can include translating a first preform tube 600into communication with a die 510 and simultaneously translating asecond preform tube 610 out of communication with the die 510. Forexample, the first preform tube 600 can be spaced apart from a secondpreform tube 610 and the first and second preform tubes 600,610 can bephysically coupled or connected, such as by a supporting member 620. Thefirst and second preform tubes 600,610 can simultaneously translate byrotating the connected first and second preform tubes about a centralaxis 630. During such rotation, the preform tubes can remain in theirgeneral orientation, such as in a vertical orientation relative to alevel surface. In other words, during such rotation, the first end 300of the preform tube 200 can remain at a lower elevation than the secondend 310 of the preform tube 200.

Referring again to FIG. 1, the method of forming a PTFE articledescribed herein can further include extruding the preform from thepreform tube. For example, a piston 700 can be arranged to force thecompacted mixture 320 (i.e. preform) through the die and through the dieopening. Paste extrusion differs from traditional extrusion in that thematerial being extruded is not melt-processable and does not flow whenheated above its melting point. Instead, the compacted raw materialmixture is pushed through a die.

FIG. 11B illustrates one example of a die 510 according to certainembodiments. The die 510 can have a first cross-sectional area D_(CSA1)at a first opening 710, nearest the first end of the preform tube (whenconnected), and a second cross-sectional area D_(CSA2) at a secondopening 720. The second opening 720 being opposite the first opening 710of the die 510. The first cross-sectional area D_(CSA1) at the firstopening 710 can be greater than the cross-sectional area D_(CSA2) at thesecond opening 720. This metric is often referred to as the “reductionratio.” The reduction ratio is a measure of the amount of compaction ofthe raw material that occurs during extrusion in the die.

In embodiments described herein, the die can have a ratio of the firstcross-sectional area to the second cross-sectional area (reductionratio) of at least 50, at least 60, at least 70, at least 80, at least85, or even at least 90. Further, a ratio of the first cross-sectionalarea to the second cross-sectional area can be no greater than 200, nogreater than 160, no greater than 120, or even no greater than 105. Inparticular, a ratio of the first cross-sectional area to the secondcross-sectional area can be in a range of any of the minimum and maximumvalues described above, such as in a range of 50 to 200, 60 to 160, oreven 80 to 120.

Without wishing to be bound by theory, the inventors discovered thatusing a die having a reduction ratio as detailed below resulted inimprovements in the physical properties and dimensional stability of thePTFE article. Traditional paste extrusion involving preforms having aloading of PTFE of about 3 lbs or less incorporate a die having areduction ratio of below about 50. It was heretofore unknown thatincreasing the reduction ratio to the values discussed below could orwould improve the PTFE article's physical properties and dimensionalstability, especially with the large preforms discussed herein.

Referring again to FIG. 1, certain embodiments of methods of forming aPTFE article described herein can further include calendering 70 thePTFE article after extrusion. Calendering reduces the thickness of thePTFE article by feeding the article through a set of rollers having apredetermined gap therebetween which is smaller than the nominalthickness of the PTFE article before calendering, as is well understoodin the art.

In certain embodiments, the PTFE article can have a first averagethickness, before calendering, and a second average thickness aftercalendering. The second average thickness is less than the first averagethickness. One useful parameter to describe the calendering operation isthe ratio of the first thickness to the second thickness. In certainembodiments, a ratio of the first thickness to the second thickness canbe at least 1.1, at least 1.5, at least 2, at least 2.5, or even atleast 3. Further, a ratio of the first thickness to the second thicknesscan be no greater than 20, no greater than 15, or even no greater than10. In particular embodiments, a ratio of the first thickness to thesecond thickness can be in a range of any of the minimum and maximumvalues described above, such as in a range of 1.1 to 20, 2 to 15, oreven 2.5 to 10.

In further embodiments, more than one calendering operation can beperformed. For example, in certain embodiments, a method of forming aPTFE article can include one or more calendering steps, such as, atleast 1 or even at least 2 calendering steps. When at least 2calendering steps are used, in certain embodiments, the at least 2calendering steps can be sequential, or having intervening stepstherebetween.

Referring again to FIG. 1, the methods of forming a PTFE articledescribed herein can further include drying 80 the PTFE article toremove or drive off the lubricant. Drying can be accomplished by anyuseful method, and in certain embodiments, includes contacting the PTFEarticle with pressurized, heated drums. In particular embodiments,drying is conducted such that less than 5% by weight, less than 3% byweight, less than 1% by weight, or is even essentially none of thelubricant remains in the PTFE article.

Referring again to FIG. 1, after drying, the article can be wound 90into a roll as is understood in the art.

Typically, after winding, the roll can be cut lengthwise tosubstantially reduce the width variation of the PTFE article. In fact, aparticular advantage of the present disclosure, as will be described inmore detail below, is the achievement of a low width variation in thePTFE article. Having a low width variation is desirable as it can reducethe amount of waste or loss which traditionally occurs in themanufacture of PTFE articles, typically referred to as the yield loss orwidthwise yield loss.

In certain embodiments, the methods described herein can further includean expanding operation as is understood in the art. Expanded orlow-density PTFE articles can include any PTFE article which has beenmanipulated to reduce the density of the PTFE article as is commonlyunderstood in the art. For example, a PTFE article can be uniaxially orbiaxially expanded. Further, a PTFE article can be expanded in themachine-direction and/or cross machine direction. As a specific example,expansion operations can include stretching a PTFE article on a lowdensity stretcher and expanding at a high temperature in the machinedirection to a final desired thickness and specific gravity. ExpandedPTFE articles can be used in wire or cable assemblies, and inparticular, coaxial cables as described in more detail below. In veryparticular embodiments, the cable or wire assemblies, and particularlythe coaxial cable assemblies can be used in an aircraft.

Another aspect of the present disclosure is directed to a PTFE article,and particularly to a PTFE article constructed according the methodsdescribed above. As discussed in detail herein, a particular advantageof the present disclosure is the construction of a PTFE article havingsuperior dimensional stability (i.e. low variation) and performancestability, particularly over long lengths. Traditional paste extrudedPTFE article production for long lengths was accomplished bysuccessively paste extruding small preforms. While the successive pasteextrusion of small preforms allowed for formation of a continuousarticle over longer lengths, the area where the two preforms metresulted in a noticeable and measurable joint or seam in the extrudedPTFE article. These joints or seams often have weak mechanical andelectrical properties and can cause extreme deviations and variation inthe PTFE dimensional parameters. In many industries and uses, andparticularly in cabling or wire assemblies in the aerospace field, suchweak mechanical properties and deviations in dimensional parameters areincreasingly undesirable and often wholly unacceptable. Accordingly, theinventors have discovered novel methods, as discussed in detail above,to form a novel PTFE article that has superior mechanical properties anddimensional stability, particularly over long lengths. While theimprovements over long lengths are extremely significant, it is furthernoted that the methods described above have also unexpectedly realizedimprovement in mechanical properties and dimensional stabilityregardless of the length.

The PTFE article described herein can have a number of different desireddimensions depending on the intended use. Referring to FIG. 12A, whichillustrates a segment of PTFE article 800, the PTFE article describedherein can have a length L, a width W, a thickness T, and across-sectional area CSA. The length is also referred to as the machinedirection, and the width is also referred to as the cross direction. Thecross-sectional area CSA can be determined by multiplying the width andthe thickness at a given point along the length.

The length can be greater than the width, and the width can be greaterthan the thickness. In particular embodiments, a ratio of the length tothe width can be at least 100, at least 500, at least 1,000, or even, atleast 5,000. Further a ratio of the length to the width can be nogreater than 1,000,000, no greater than 100,000, or even no greater than50,000. Moreover, in particular embodiments, the PTFE article can have aratio of its length to its width in a range of any of the minimum andmaximum values described above, such as in a range of 5,000 to 50,000.

In further particular embodiments, a ratio of the width to the thicknesscan be at least 50, at least 100, or even at least 1,000. Further, aratio of the width the thickness can be no greater than 50,000, nogreater than 25,000, or even no greater than 10,000. Moreover, inparticular embodiments, the PTFE article can have a ratio of its widthto its thickness in a range of any of the minimum and maximum valuesdescribed above, such as in a range of 100 to 10,000.

In certain embodiments, the PTFE article described herein can have acontinuous length of at least 60 meters, at least 100 meters, at least250 meters, at least 320 meters, at least 500 meters, at least 750meters, at least 1,000 meters, at least 1,250 meters, at least 1,500meters, at least 1,750 meters, or even at least 2,000 meters. Inparticular embodiments, the PTFE article described herein can have acontinuous length of at least 320 meters. In further embodiments, thePTFE article described herein can have a continuous length of no greaterthan 10,000 meters, no greater than 6,000 meters, or even no greaterthan 3,000 meters. In particular embodiments, the PTFE article can havea continuous length in a range of any of the minimum and maximum valuesdescribed above, such as, 60 meters to 10,000 meters or even 320 metersto 6,000 meters.

In certain embodiments, the PTFE article can have an average, uncutwidth of at least 0.001 meters, at least 0.01 meters, at least 0.1meters or even at least 0.2 meters. In further embodiments, the PTFEarticle can have an average, uncut width of no greater than 2 meters, nogreater than 1 meter, or even no greater than 0.5 meters. In particularembodiments, the PTFE article can have an average, uncut width in arange of any of the minimum and maximum values described above, such as,in a range of 0.001 meters to 2 meters, or even 0.2 meters to 0.5meters.

The nominal width values described above are referred to as an “uncutwidth.” In further embodiments, the width values described herein can befor a finished or cut width. Traditionally, after completion of thefinishing operations, i.e. calendering and drying, the article can becut along its length to reduce the width of the PTFE article asdescribed above. For example, the width of the article can first betrimmed or cut to reduce the amount of width variation along the lengthof the roll. In this type of operation, care is taken to cut the entireroll to match the smallest width seen along the length to therebygreatly diminish any width variation. In fact, a particular advantage ofthe present disclosure is the reduction in yield loss resulting from animproved width variation. The yield loss can be calculated as a weightpercentage of the usable material from the as extruded material. Forexample, the yield loss can be calculated according to the followingequation:YL=((M _(B) −M _(A))/(M _(B)))*100%

wherein YL refers to Yield Loss, M_(B) refers to the mass of the PTFEroll before cutting, and M_(A) refers to the mass of the PTFE roll aftercutting.

In certain embodiments, the PTFE article described herein can have awidthwise yield loss (also known as the cross-direction yield loss) ofno greater than 20%, no greater than 18%, no greater than 16%, nogreater than 14%, no greater than 12%, no greater than 10%, no greaterthan 8%, or even no greater than 7%, or still even no greater than 5%.In even further embodiments, the PTFE article described herein can havea widthwise yield loss at least 1% or even at least 3%. In even furtherembodiments, the PTFE article described herein can have a widthwiseyield loss in a range of any of the minimum and maximum values describedabove, such as in a range of 1% to 20%, or even in a range of 1% to 10%.

In certain embodiments, the PTFE article can have a mean averagethickness of no greater than 1,000 microns, no greater than 500 microns,no greater than 250 microns, no greater than 200 microns, no greaterthan 150 microns, no greater than 125 microns, no greater than 100microns, no greater than 75 microns, or even no greater than 60 micronsacross the continuous length. In further embodiments, the PTFE articlecan have a mean average thickness of at least 0.1 microns, at least 1micron, at least 5 microns, at least 10 microns, at least 20 microns, atleast 30 microns, or even at least 40 microns. In particularembodiments, the PTFE article can have a mean average thickness in arange of any of the minimum and maximum values described above, such as,in a range of 0.1 microns to 1,000 microns, or even 1 micron to 500microns. It is particularly noted that embodiments described herein canachieve a very low thickness variation as described below at very lowthicknesses.

As discussed above, a particular advantage of the present disclosure isthe reduction and even elimination of joints or seams along variouslengths. In certain embodiments, the PTFE article can have no more than5 joints, no more than 4 joints, no more than 3 joints, no more than 2joints, no more than 1 joint, or is even essentially joint free.Further, the PTFE article can have no more than 5 joints, no more than 4joints, no more than 3 joints, no more than 2 joints, no more than 1joint, or is even essentially joint free over any of the continuouslengths described above, such as a continuous length of 60 meters, 100meters, 250 meters, 320 meters, 500 meters, 750 meters, 1,000 meters,1,250 meters, 1,500 meters, 1,750 meters, or even 2,000 meters. In veryparticular embodiments, the PTFE can be essentially joint free over acontinuous length of at least 100 meters, or even at least 300 meters,or even at least 1,500 meters.

Many different features described above have enabled achievement of asignificantly improved total thickness variation described below,particularly along the continuous lengths described above. The totalthickness variation is the difference between the maximum thickness andminimum thickness along a given length of the article. To determine thetotal thickness variation, individual thickness measurements can betaken at various points along the length and width. For example, in themethods and examples described herein, the sampling frequency was 10measurements per second, and the web speed varied between 90 to 200 feetper minute. The results are analyzed to find the minimum thickness andthe maximum thickness. The total thickness variation can then becalculated by subtracting the minimum thickness from the maximumthickness. The individual thickness measurements can be measured by, forexample, shadowcasting techniques, a drop gauge, or any other usefulmethod to measure a thickness. The measurements can be taken at multiplepoints across the width. For example, in the methods and examplesdescribed herein, measurements were taken at 1.5 inches from each edgeof the PTFE article.

In certain embodiments, the PTFE article described herein can have atotal thickness variation of no greater than 20 microns, no greater than18 microns, no greater than 16 microns, no greater than 14 microns, nogreater than 12 microns, no greater than 10 microns, no greater than 8microns, no greater than 7 microns, or even no greater than 5 microns.In further embodiments, the PTFE article can have a total thicknessvariation of at least 0.1 microns, at least 1 micron, or even at least 2microns. In particular embodiments, the PTFE article can have a totalthickness variation in a range of any of the minimum and maximum valuesdescribed above, such as, in a range of 0.1 microns to 20 microns, oreven 1 micron to 16 microns, or even 2 microns to 10 microns.

In particular, it is to be understood that the total thickness variationvalues described above can apply over a continuous length as describedabove, such as a length of 60 meters, 100 meters, 250 meters, 320meters, 500 meters, 750 meters, 1,000 meters, 1,250 meters, 1,500meters, 1,750 meters, or even 2,000 meters. It is to be understood thatthe PTFE article does not have to be the exact length described above,just that the recited thickness variation applies over the specifiedlength.

Further, it is to be understood that the total thickness variationvalues described above are independent of the total mean averagethickness and can apply at the various different mean averagethicknesses as described above. For example, in particular embodiments,the PTFE article can have a total thickness variation of less than 20microns and a mean average thickness in a range of 30 microns to 500microns, or even 30 microns to 130 microns. In fact, a particularadvantage of embodiments of the present disclosure is the achievement ofthe low total thickness variations described herein at particularly lowmean average thicknesses described herein.

In certain embodiments, the thickness variation can also be described asa percent variance from the mean average thickness. The percentthickness variation can be calculated as follows:% TV=+/−((TTV/2)/(T _(AVG)))*100%

wherein % TV represents percent thickness variation; TTV representstotal thickness variation, as described above; and T_(AVG) representsthe mean average thickness variation.

For example, an article that has a total thickness variation of 20microns, and a mean average thickness of 50 microns, would have apercent thickness variation of +/−20%. As a further example, an articlethat has a total thickness variation of 5 microns, and a mean averagethickness of 50 microns, the article would have a percent thicknessvariation of 5%. As a third example, an article that has a totalthickness variation of 20 microns, and a mean average thickness of 120microns, the article would have a percent thickness variation of 8.3%.

In certain embodiments of the present disclosure, the PTFE article canhave a percent thickness variation of less than 20%, no greater than18%, no greater than 16%, no greater than 14%, no greater than 12%, nogreater than 10%, no greater than 8%, no greater than 6%, or even nogreater than 5%. In particular embodiments, the PTFE article can have apercent thickness variation of less than 20%, no greater than 10%, oreven no greater than 5%.

The PTFE article can have the recited percent thickness variation overany of the continuous lengths described above, such as a length of 60meters, 100 meters, 250 meters, 320 meters, 500 meters, 750 meters,1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even 2,000meters. It is to be understood that the PTFE article does not have to bethe exact length described above, just that the recited thicknessvariation applies over the specified length.

The PTFE article can have the recited % thickness variation at any ofthe different ranges of mean average thicknesses discussed above. Inparticular embodiments, the PTFE article can have a percent thicknessvariation of less than 20%, no greater than 10%, or even no greater than5% and a mean average thickness in a range of 20 microns to 150 microns.In even more particular embodiments, the PTFE article can have a percentthickness variation of less than 20%, no greater than 10%, or even nogreater than 5% and a mean average thickness of less than 80 microns. Avery particular advantage of the aspects of the present disclosure isthe achievement of the improved thickness variation at low mean averagethicknesses, such as mean average thicknesses of less than 250 microns,and particularly less than 150 microns, such as less than 100 microns oreven less than 80 microns.

Another way to characterize the improved thickness variation is thestandard deviation of the average thickness. The average thickness canbe calculated as described herein. In certain embodiments, the standarddeviation of the average thickness can be no more than 2.3 microns, nomore than 2.2 microns, no more than 2.1 microns, no more than 2.0microns, no more than 1.9 microns, no more than 1.8 microns, no morethan 1.7 microns, no more than 1.6 microns, no more than 1.5 microns, nomore than 1.4 microns, no more than 1.3 microns, no more than 1.2microns, no more than 1.1 microns, no more than 1 microns, or even nomore than 0.9 microns over a continuous length of 60 meters, 100 meters,250 meters, 320 meters, 500 meters, 750 meters, 1,000 meters, 1,250meters, 1,500 meters, 1,750 meters, or even 2,000 meters. In furtherembodiments, the standard deviation of the average thickness can be atleast 0.01 microns, or even at least 0.1 microns, or even at least 0.2microns. Moreover, in certain embodiments, the standard deviation of theaverage thickness can be in a range between any of the maximum andminimum values provided above. In very particular embodiments, the PTFEarticle can have a standard deviation of average thickness of less than2.3 microns over a continuous length of 80 meters. In still even furthervery particular embodiments, the PTFE article can have a standarddeviation of average thickness of less than 1.5 microns over acontinuous length of 320 meters. It is further to be understood that thestandard deviation of the average thickness values described above canbe present at any of the mean average thicknesses recited herein, suchas less than 250 microns.

Yet another way to characterize the improvements in the PTFE article isthe article's maximum low spot thickness Similar to the thicknessvariation, the maximum low spot thickness is determined relative to themean average thickness. The maximum low spot thickness can be calculatedas follows:Maximum Low Spot Thickness=(T _(AVG) −T _(MIN))/(T _(AVG))*100%

where T_(AVG) refers to the mean average thickness over a particularlength and T_(MIN) refers to the lowest thickness over the same length.In certain embodiments of the present disclosure, the PTFE article canhave a maximum low spot thickness of less than 30%, less than 25%, lessthan 20%, no greater than 18%, no greater than 16%, no greater than 14%,no greater than 12%, no greater than 10%, no greater than 8%, no greaterthan 6%, or even no greater than 5%. In particular embodiments, the PTFEarticle can have a maximum low spot thickness of less than 20%, nogreater than 10%, or even no greater than 5%.

The PTFE article can have the recited maximum low spot thickness overany of the continuous lengths described above, such as a length of 60meters, 100 meters, 250 meters, 320 meters, 500 meters, 750 meters,1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even 2,000meters. It is to be understood that the PTFE article does not have to bethe exact length described above, just that the recited thicknessvariation applies over the specified length.

The PTFE article can have the recited maximum low spot thickness at anyof the different ranges of mean average thicknesses discussed above. Inparticular embodiments, the PTFE article can have a percent thicknessvariation of less than 20%, no greater than 10%, or even no greater than5% and a mean average thickness in a range of 20 microns to 250 microns.In even more particular embodiments, the PTFE article can have a maximumlow spot thickness of less than 20%, no greater than 10%, or even nogreater than 5% and a mean average thickness of less than 80 microns. Avery particular advantage of the aspects of the present disclosure isthe achievement of the improved maximum low spot thickness at very lowthicknesses, such as at average thicknesses of less than 50 microns.

The cross-sectional area of the PTFE article can be determined bymultiplying the width by the thickness at a given point along thelength.

In certain embodiments, the mean average cross-sectional area of thePTFE article along a given length can be at least 0.01 cm², 0.02 cm², oreven at least 0.035 cm². In further embodiments, the PTFE article canhave a mean average cross-sectional area of the PTFE along a givenlength of no greater than 2 cm², no greater than 1.0 cm² no greater than1.5 cm², no greater than 1 cm², or even no greater than 0.8 cm². In evenfurther embodiments, the PTFE article can have a mean averagecross-section area of the PTFE article along a given length in a rangeof any of the minimum and maximum values described above, such as in arange of 0.01 cm² to 2 cm², or even 0.035 cm² to 1.9 cm². It is to beunderstood that the mean average cross-sectional area of the PTFEarticle is measured before any cutting or trimming operation in thewidthwise direction.

In certain embodiments, the PTFE article described herein can have anaverage specific gravity of at least 1.4, at least 1.45, at least 1.51,or even at least 1.6 along a length of the PTFE article. In furtherembodiments, the PTFE article described herein can have an averagespecific gravity of no greater than 2.5, no greater than 2.2, no greaterthan 2.0, no greater than 1.9, or even no greater than 1.8. Inparticular embodiments, the PTFE article can have an average specificgravity in a range of any of the minimum and maximum values describedabove, such as in a range of 1.4 to 2.5, 1.51 to 2.0, or even 1.6 to1.9.

In certain embodiments, the PTFE article can have a particular porosity,which can be quantified by Gurley Permeability. Gurley permeabilitymeasures the time for a volume of air to flow through a sheet ofmaterial. The Gurley tester is well known in the paper industry, and ahigher value indicates a less permeable sheet. The Gurley permeabilitycan be measured according to JIS P 8117. In certain embodiments, a PTFEarticle described herein can have an average Gurley Permeability of atleast 10 seconds, at least 25 seconds, at least 50 seconds, at least 60seconds, at least 70 seconds, at least 75 seconds, at least 80 seconds,at least 85 seconds, or even at least 90 seconds. In furtherembodiments, the PTFE article described herein can have an averageGurley Permeability of no greater than 500 seconds, no greater than 200seconds, or even no greater than 100 seconds, or even no greater than 80seconds. In particular embodiments, the PTFE article described hereincan have an average Gurley Permeability in a range of any of the minimumand maximum values described above, such as in a range of 10 seconds to80 seconds.

One useful parameter to describe the quality of a PTFE article is itsmachine direction tensile stress at a maximum load, which characterizesthe PTFE article's mechanical strength in the machine direction. Themachine direction tensile stress at a maximum load is commonly used andunderstood by one of ordinary skill in the art. The values of themachine direction tensile stress at a maximum load described herein aremeasured with an Instron tensile tester in accordance with ASTM-D882.

In certain embodiments, the machine direction tensile stress at amaximum load can be at least 1,900 psi, at least 2,100 psi, at least2,300 psi, or even at least 2,500 psi. In further embodiments, themachine direction tensile stress at a maximum load can be no greaterthan 10,000 psi, no greater than 9,000 psi, or even no greater than7,000 psi. In particular embodiments, the machine direction tensilestress at a maximum load can be in a range of any of the minimum andmaximum values described above, such as, in a range of 1,900 psi to10,000 psi, 2,100 psi to 9,000 psi, or even 2,300 psi to 7,000 psi.

Another useful parameter to describe the quality of a PTFE article isits cross-direction elongation to break, which characterizes the PTFEarticle's mechanical strength in the cross-machine direction. Thecross-direction elongation to break is commonly used and understood byone of ordinary skill in the art. The values of the cross-directionelongation to break described herein are measured with an Instrontensile tester in accordance with ASTM-D882.

In certain embodiments, the PTFE article can have a cross-directionelongation to break of at least 500%, at least 600%, at least 800%, atleast 900%. In further embodiments, the PTFE article can have across-direction elongation to break of no greater than about 1000%. Inparticular embodiments, the PTFE article can have a cross-directionelongation to break in a range of any of the minimum and maximum valuesdescribed above, such as in a range of 600% to 1000%.

Another particular advantage of the present disclosure is the lowvariability of the cross-direction elongation to break at variouslocations across the width of the PTFE article. For example, asdescribed in more detail herein, after extruding and finishing a PTFEarticle, the article is often cut lengthwise to generate multiplearticles having a smaller width than the original article. Thus, it isdesired to have a consistency of the cross-direction elongation to breakbetween the outer ends and the middle of the PTFE article so there isconsistency between the multiple cut rolls having a smaller width.

In certain embodiments, the PTFE article described herein can have atotal variability between the outer ends and the middle of no greaterthan 20%, no greater than 15%, no greater than 10%, or even no greaterthan 5%. To measure the total variability of the cross-directionelongation to break, measurements are taken at the middle of the rollbefore cutting and at a point which is 10% of the total width from bothouter ends. The total variability of the cross-direction elongation tobreak can then be determined by subtracting the maximum from theminimum, dividing by the average, and multiplying by 100%.

Other useful parameters to describe the effectiveness of the PTFEarticle described herein, particularly when it is employed in anelectrical assembly, such as a cable or wire assembly and particularlyin a coaxial cable, is the dielectric constant and loss tangent of thePTFE article, and even more particularly the variability of thedielectric constant and loss tangent over a given length of the PTFEarticle.

The dielectric constant (_(r)) of a PTFE article is a measure of thecapacitance of a construction using the PTFE article as a dielectric,compared to the capacitance of a similar construction in which thedielectric is a vacuum. The loss tangent (tan) of the PTFE article, alsocalled the dissipation factor, is a measure of the energy dissipated bythe PTFE article when in an oscillating electric field. Specifically, itis a determination of the degree to which the phase difference betweenthe current and the voltage of the charge motion generated in the PTFEarticle by an oscillating field in an adjacent conductor is shifted from90 degrees. It is expressed as the tangent of the angular phasedifference. The dielectric constant of the PTFE article employed as thedielectric material in a coaxial cable determines the speed at which anelectrical signal will travel in that coaxial cable. Signal propagationspeed is expressed relative to the speed of light in a vacuum, which isroughly 3.0×10¹⁰ cm/sec. The dielectric constant of a hard vacuum(space) is defined as 1.00. Higher dielectric constants will result inslower signal propagation speed. Loss tangent is a measure of how muchof the power of a signal is lost as it passes along a transmission lineon a dielectric material. Testing of the dielectric constant can beconducted at frequencies of 1 MHz and 20 GHz. At 1 MHz, the dielectricconstant can be measured according to the guidelines of ASTM D-150. Inparticular, the dielectric constant can be measured using aparallel-plate test fixture with 38 mm diameter electrodes. The electricfield can be linear and perpendicular to the plane of the samples. At 20GHz, testing can be conducted using the guidelines ofIPC-TM-650-2.5.5.13 Relative Permittivity and Loss Tangent Using aSplit=Cylinder Resonator in accordance with the guidelines of D2520-01.Results can be obtained using a split-cylinder cavity resonator andNational Institute of Standards and Technology (NIST) SplitC Version 1.0software. All measurements can be conducted under ambient conditions of25 degrees Celsius and 48% Relative Humidity (RH). Each test sample canbe comprised of two or more 2 inch by 2 inch pieces of film. Usingmulti-piece stacks can improve measurement accuracy.

In certain embodiments, a PTFE article described herein can have anaverage dielectric constant of no greater than 3, no greater than 2.7,no greater than 2.5, no greater than 2.3, no greater than 2.1, nogreater than 1.9, no greater than 1.7, or even no greater than 1.5.Further, a PTFE article described herein can have an average dielectricconstant of at least 0.5, at least 1, or even at least 1.3. Inparticular embodiments, a PTFE article described herein can have anaverage dielectric constant in a range of any of the minimum and maximumvalues described above, such as in a range of 1 to 3.

Further, another useful measure of the performance of a PTFE articledescribed herein is the total dielectric constant variation along agiven length. To determine the total dielectric constant variation alonga given length, the dielectric constant is measured as discussed aboveat an interval of 5 meters over the specified length. The measurementsare then analyzed to determine the minimum dielectric constant and themaximum dielectric constant over the given length. The total dielectricconstant variation along a given length is then calculated as thedifference between the minimum and maximum dielectric constant.

In certain embodiments, a PTFE article described herein can have a totaldielectric constant variation of no greater than 1, no greater than 0.8,no greater than 0.6, no greater than 0.5, no greater than 0.4, nogreater than 0.3, no greater than 0.2, no greater than 0.1, or even nogreater than 0.05. Further, a PTFE article described herein can have atotal dielectric constant variation of at least 0.005, or even nogreater than 0.01. In particular embodiments, a PTFE article describedherein can have a total dielectric constant variation in a range of anyof the minimum and maximum values described above, such as in a range of0.01 to 0.5.

In certain embodiments, the PTFE article described herein can have anaverage dielectric constant and/or a total dielectric constant variationas recited above over a continuous length of at least 60 meters, atleast 100 meters, at least 250 meters, at least 320 meters, at least 500meters, at least 750 meters, at least 1,000 meters, at least 1,250meters, at least 1,500 meters, at least 1,750 meters, or even at least2,000 meters. In particular embodiments, the PTFE article describedherein can have an average dielectric constant and/or a total dielectricconstant variation as recited above over a continuous length of at least320 meters. In further embodiments, the PTFE article described hereincan have an average dielectric constant and/or a total dielectricconstant variation as recited above over a continuous length of nogreater than 10,000 meters, no greater than 6,000 meters, or even nogreater than 3,000 meters. In particular embodiments, the PTFE articlecan have an average dielectric constant and/or a total dielectricconstant variation as recited above over a continuous length in a rangeof any of the minimum and maximum values described above, such as, 60meters to 10,000 meters or even 320 meters to 6,000 meters.

In certain embodiments, the PTFE article described herein can have anaverage loss tangent (dissipation factor (tan δ)) of no greater than0.0003, no greater than 0.0002, no greater than 0.00013, no greater than0.0001, no greater than 0.00005, no greater than 0.00002, or even nogreater than 0.00001, or even no greater than 0.000005. In furtherembodiments, the PTFE article described herein can have an average losstangent (dissipation factor (tan δ)) of at least 0.00000001 or even atleast 0.0000001. Moreover, the PTFE article described herein can have anaverage loss tangent (dissipation factor (tan δ)) in a range of any ofthe minimum and maximum values described above, such as in a range of0.0000001 to 0.0002.

Further, another useful measure of the performance of a PTFE articledescribed herein is the loss tangent variation along a given length. Todetermine the loss tangent variation along a given length, the losstangent is measured as discussed above at an interval of 5 meters overthe specified length. The measurements are then analyzed to determinethe minimum loss tangent and the maximum loss tangent over the givenlength. The loss tangent variation along a given length is thencalculated as the difference between the minimum and maximum losstangent, divided by the average loss tangent and multiplied by 100%.

In certain embodiments, the PTFE article described herein can have aloss tangent variation of no greater than 20%, no greater than 10%, nogreater than 8%, or even no greater than 5%, no greater than 3%, nogreater than 2%, no greater than 1%, or even no greater than 0.1%.Further, in certain embodiments, the PTFE article described herein canhave a loss tangent variation of at least 0.001%, at least 0.01%, oreven at least 0.1%. Moreover, in certain embodiments, the PTFE articledescribed herein can have a loss tangent variation in a range of any ofthe minimum and maximum values described above, such as in a range of0.01% to 8%, or even 0.1% to 5%. In certain embodiments, the PTFEarticle described herein can have an average loss tangent and/or a losstangent variation as recited above over a continuous length of at least60 meters, at least 100 meters, at least 250 meters, at least 320meters, at least 500 meters, at least 750 meters, at least 1,000 meters,at least 1,250 meters, at least 1,500 meters, at least 1,750 meters, oreven at least 2,000 meters. In particular embodiments, the PTFE articledescribed herein can have an average loss tangent and/or a loss tangentvariation as recited above over a continuous length of at least 320meters. In further embodiments, the PTFE article described herein canhave an average loss tangent and/or a loss tangent variation as recitedabove over a continuous length of no greater than 10,000 meters, nogreater than 6,000 meters, or even no greater than 3,000 meters. Inparticular embodiments, the PTFE article can have an average losstangent and/or a loss tangent variation as recited above over acontinuous length in a range of any of the minimum and maximum valuesdescribed above, such as, 60 meters to 10,000 meters or even 320 metersto 6,000 meters.

It is noted that the values of dielectric constant, dielectric constantvariation, loss tangent, and loss tangent variation described above, canbe obtained as measured in a low and/or high frequency of 1 MHz and 20GHz respectively.

Another aspect of the present disclosure is directed to an expanded PTFEarticle, also referred to as ePTFE. The expanded PTFE article describedherein can have a number of different desired dimensions depending onthe intended use. Referring to FIG. 12B, which illustrates a segment ofexpanded PTFE article 801, the expanded PTFE article described hereincan have a length L, a width W, a thickness T, and a cross-sectionalarea CSA. The length is also referred to as the machine direction, andthe width is also referred to as the cross direction. Thecross-sectional area CSA can be determined by multiplying the width andthe thickness at a given point along the length.

The length can be greater than the width, and the width can be greaterthan the thickness. In particular embodiments, a ratio of the length tothe width can be at least 100, at least 500, at least 1,000, or even, atleast 5,000. Further a ratio of the length to the width can be nogreater than 1,000,000, no greater than 100,000, or even no greater than50,000. Moreover, in particular embodiments, the expanded PTFE articlecan have a ratio of its length to its width in a range of any of theminimum and maximum values described above, such as in a range of 5,000to 50,000.

In further particular embodiments, a ratio of the width to the thicknesscan be at least 50, at least 100, or even at least 1,000. Further, aratio of the width the thickness can be no greater than 50,000, nogreater than 25,000, or even no greater than 10,000. Moreover, inparticular embodiments, the expanded PTFE article can have a ratio ofits width to its thickness in a range of any of the minimum and maximumvalues described above, such as in a range of 100 to 10,000.

In certain embodiments, the expanded PTFE article described herein canhave a continuous length of at least 60 meters, at least 100 meters, atleast 250 meters, at least 320 meters, at least 500 meters, at least 750meters, at least 1,000 meters, at least 1,250 meters, at least 1,500meters, at least 1,750 meters, or even at least 2,000 meters. Inparticular embodiments, the expanded PTFE article described herein canhave a continuous length of at least 320 meters. In further embodiments,the expanded PTFE article described herein can have a continuous lengthof no greater than 10,000 meters, no greater than 6,000 meters, or evenno greater than 3,000 meters. In particular embodiments, the expandedPTFE article can have a continuous length in a range of any of theminimum and maximum values described above, such as, 60 meters to 10,000meters or even 320 meters to 6,000 meters.

In certain embodiments, the expanded PTFE article can have an average,uncut width of at least 0.001 meters, at least 0.01 meters, at least 0.1meters or even at least 0.2 meters. In further embodiments, the expandedPTFE article can have an average, uncut width of no greater than 2meters, no greater than 1 meter, or even no greater than 0.5 meters. Inparticular embodiments, the expanded PTFE article can have an average,uncut width in a range of any of the minimum and maximum valuesdescribed above, such as, in a range of 0.001 meters to 2 meters, oreven 0.2 meters to 0.5 meters.

The nominal width values described above are referred to as an “uncutwidth.” In further embodiments, the width values described herein can befor a finished or cut width. Traditionally, after completion of thefinishing operations, i.e. calendering, drying, and expansion, thearticle can be cut along its length to reduce the width of the expandedPTFE article as described above. For example, the width of the articlecan first be trimmed or cut to reduce the amount of width variationalong the length of the roll. In this type of operation, care is takento cut the entire roll to match the smallest width seen along the lengthto thereby greatly diminish any width variation. In fact, a particularadvantage of the present disclosure is the reduction in yield lossresulting from an improved width variation. The yield loss can becalculated as a weight percentage of the usable material from the asextruded material. For example, the yield loss can be calculatedaccording to the following equation:YL=((M _(B) −M _(A))/(M _(B)))*100%

wherein YL refers to Yield Loss, M_(B) refers to the mass of the PTFEroll before cutting, and M_(A) refers to the mass of the expanded PTFEroll after cutting.

In certain embodiments, the expanded PTFE article described herein canhave a widthwise yield loss (also known as the cross-direction yieldloss) of no greater than 20%, no greater than 18%, no greater than 16%,no greater than 14%, no greater than 12%, no greater than 10%, nogreater than 8%, or even no greater than 7%, or still even no greaterthan 5%. In even further embodiments, the expanded PTFE articledescribed herein can have a widthwise yield loss at least 1% or even atleast 3%. In even further embodiments, the expanded PTFE articledescribed herein can have a widthwise yield loss in a range of any ofthe minimum and maximum values described above, such as in a range of 1%to 20%, or even in a range of 1% to 10%.

In certain embodiments, the expanded PTFE article can have a meanaverage thickness of no greater than 1000 microns, no greater than 500microns, no greater than 250 microns, no greater than 200 microns, nogreater than 150 microns, no greater than 125 microns, no greater than100 microns, no greater than 75 microns, or even no greater than 60microns across the continuous length. In further embodiments, theexpanded PTFE article can have a mean average thickness of at least 0.1microns, at least 1 micron, at least 5 microns, at least 10 microns, atleast 20 microns, at least 30 microns, or even at least 40 microns. Inparticular embodiments, the expanded PTFE article can have a meanaverage thickness in a range of any of the minimum and maximum valuesdescribed above, such as, in a range of 0.1 microns to 1000 microns, oreven 1 micron to 500 microns. It is particularly noted that embodimentsdescribed herein can achieve a very low thickness variation as describedbelow at very low thicknesses.

As discussed above, a particular advantage of the present disclosure isthe reduction and even elimination of joints or seams along variouslengths. In certain embodiments, the expanded PTFE article can have nomore than 5 joints, no more than 4 joints, no more than 3 joints, nomore than 2 joints, no more than 1 joint, or is even essentially jointfree. Further, the expanded PTFE article can have no more than 5 joints,no more than 4 joints, no more than 3 joints, no more than 2 joints, nomore than 1 joint, or is even essentially joint free over any of thecontinuous lengths described above, such as a continuous length of 60meters, 100 meters, 250 meters, 320 meters, 500 meters, 750 meters,1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even 2,000meters. In very particular embodiments, the expanded PTFE can beessentially joint free over a continuous length of at least 100 meters,or even at least 300 meters.

Many different features described above have enabled achievement of asignificantly improved total thickness variation described below,particularly along the continuous lengths described above. The totalthickness variation is the difference between the maximum thickness andminimum thickness along a given length of the expanded article. Todetermine the total thickness variation, individual thicknessmeasurements can be taken at various points along the length and width.For example, in the methods and examples described herein, the samplingfrequency was 10 per second, and the web speed varied between 90 to 200feet per minute. The results are analyzed to find the minimum thicknessand the maximum thickness. The total thickness variation can then becalculated by subtracting the minimum thickness from the maximumthickness. The individual thickness measurements can be measured by, forexample, shadowcasting techniques, a drop gauge, or any other usefulmethod to measure a thickness. The measurements can be taken at multiplepoints across the width. For example, in the methods and examplesdescribed herein, measurements were taken at 1.5 inches from each edgeof the PTFE article. Measurements were taken after extrusion and beforestretching. The dimensional tolerances achieved after extrusion weremaintained after expansion.

In certain embodiments, the expanded PTFE article described herein canhave a total thickness variation of no greater than 20 microns, nogreater than 18 microns, no greater than 16 microns, no greater than 14microns, no greater than 12 microns, no greater than 10 microns, nogreater than 8 microns, no greater than 7 microns, or even no greaterthan 5 microns. In further embodiments, the expanded PTFE article canhave a total thickness variation of at least 0.1 microns, at least 1micron, or even at least 2 microns. In particular embodiments, theexpanded PTFE article can have a total thickness variation in a range ofany of the minimum and maximum values described above, such as, in arange of 0.1 microns to 20 microns, or even 1 micron to 16 microns, oreven 2 microns to 10 microns.

In particular, it is to be understood that the total thickness variationvalues described above can apply over a continuous length as describedabove, such as a length of 60 meters, 100 meters, 250 meters, 320meters, 500 meters, 750 meters, 1,000 meters, 1,250 meters, 1,500meters, 1,750 meters, or even 2,000 meters. It is to be understood thatthe expanded PTFE article does not have to be the exact length describedabove, just that the recited thickness variation applies over thespecified length.

Further, it is to be understood that the total thickness variationvalues described above are independent of the total mean averagethickness and can apply at the various different mean averagethicknesses as described above. For example, in particular embodiments,the expanded PTFE article can have a total thickness variation of lessthan 20 microns and a mean average thickness in a range of 30 microns to500 microns, or even 30 microns to 130 microns.

In certain embodiments, the thickness variation can also be described asa percent variance from the mean average thickness. The percentthickness variation can be calculated as follows:% TV=+/−((TTV/2)/(T _(AVG)))*100%

wherein % TV represents percent thickness variation; TTV representstotal thickness variation, as described above; and T_(AVG) representsthe mean average thickness variation.

For example, an article that has a total thickness variation of 20microns and a mean average thickness of 50 microns would have a percentthickness variation of +/−20%. As a further example, an article that hasa total thickness variation of 5 microns and a mean average thickness of50 microns would have a percent thickness variation of 5%. As a thirdexample, an article that has a total thickness variation of 20 micronsand a mean average thickness of 120 microns would have a percentthickness variation of 8.3%.

In certain embodiments of the present disclosure, the expanded PTFEarticle can have a percent thickness variation of less than 20%, nogreater than 18%, no greater than 16%, no greater than 14%, no greaterthan 12%, no greater than 10%, no greater than 8%, no greater than 6%,or even no greater than 5%. In particular embodiments, the expanded PTFEarticle can have a percent thickness variation of less than 20%, nogreater than 10%, or even no greater than 5%.

The expanded PTFE article can have the recited percent thicknessvariation over any of the continuous lengths described above, such as alength of 60 meters, 100 meters, 250 meters, 320 meters, 500 meters, 750meters, 1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even2,000 meters. It is to be understood that the expanded PTFE article doesnot have to be the exact length described above, just that the recitedthickness variation applies over the specified length.

The expanded PTFE article can have the recited % thickness variation atany of the different ranges of mean average thicknesses discussed above.In particular embodiments, the expanded PTFE article can have a percentthickness variation of less than 20%, no greater than 10%, or even nogreater than 5% and a mean average thickness in a range of 20 microns to150 microns. In even more particular embodiments, the expanded PTFEarticle can have a percent thickness variation of less than 20%, nogreater than 10%, or even no greater than 5% and a mean averagethickness of less than 80 microns. A very particular advantage of theaspects of the present disclosure is the achievement of the improvedthickness variation at very low mean average thicknesses, such as meanaverage thicknesses of less than 250 microns, less than 150 microns,less than 100 microns, or even less than 80 microns.

Another way to characterize the improved thickness variation is thestandard deviation of the average thickness. The average thickness canbe calculated as described herein. In certain embodiments, the standarddeviation of the average thickness can be no more than 2.3 microns, nomore than 2.2 microns, no more than 2.1 microns, no more than 2.0microns, no more than 1.9 microns, no more than 1.8 microns, no morethan 1.7 microns, no more than 1.6 microns, no more than 1.5 microns, nomore than 1.4 microns, no more than 1.3 microns, no more than 1.2microns, no more than 1.1 microns, no more than 1 micron, or even nomore than 0.9 microns over a continuous length of 60 meters, 100 meters,250 meters, 320 meters, 500 meters, 750 meters, 1,000 meters, 1,250meters, 1,500 meters, 1,750 meters, or even 2,000 meters. In furtherembodiments, the standard deviation of the average thickness can be atleast 0.01 microns, or even at least 0.1 microns, or even at least 0.2microns. Moreover, in certain embodiments, the standard deviation of theaverage thickness can be in a range between any of the maximum andminimum values provided above. In very particular embodiments, theexpanded article can have a standard deviation of average thickness ofless than 2.3 microns over a continuous length of 80 meters. In stilleven further very particular embodiments, the expanded article can havea standard deviation of average thickness of less than 1.5 microns overa continuous length of 320 meters. It is further to be understood thatthe standard deviation of the average thickness values described abovecan be present at any of the mean average thicknesses recited herein.

Yet another way to characterize the improvements in the expanded PTFEarticle is the expanded article's maximum low spot thickness. Similar tothe thickness variation, the maximum low spot thickness is determinedrelative to the mean average thickness. The maximum low spot thicknesscan be calculated as follows:Maximum Low Spot Thickness=(T _(AVG) −T _(MIN))/(T _(AVG))*100%

where T_(AVG) refers to the mean average thickness over a particularlength and T_(MIN) refers to the lowest thickness over the same length.In certain embodiments of the present disclosure, the expanded PTFEarticle can have a maximum low spot thickness of less than 30%, lessthan 25%, less than 20%, no greater than 18%, no greater than 16%, nogreater than 14%, no greater than 12%, no greater than 10%, no greaterthan 8%, no greater than 6%, or even no greater than 5%. In particularembodiments, the expanded PTFE article can have a maximum low spotthickness of less than 20%, no greater than 10%, or even no greater than5%.

The expanded PTFE article can have the recited maximum low spotthickness over any of the continuous lengths described above, such as alength of 60 meters, 100 meters, 250 meters, 320 meters, 500 meters, 750meters, 1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even2,000 meters. It is to be understood that the expanded PTFE article doesnot have to be the exact length described above, just that the recitedthickness variation applies over the specified length.

The expanded PTFE article can have the recited maximum low spotthickness at any of the different ranges of mean average thicknessesdiscussed above. In particular embodiments, the expanded PTFE articlecan have a percent thickness variation of less than 20%, no greater than10%, or even no greater than 5% and a mean average thickness in a rangeof 20 microns to 250 microns. In even more particular embodiments, theexpanded PTFE article can have a maximum low spot thickness of less than20%, no greater than 10%, or even no greater than 5% and a mean averagethickness of less than 80 microns. A very particular advantage of theaspects of the present disclosure is the achievement of the improvedmaximum low spot thickness at very low thicknesses, such as at averagethicknesses of less than 50 microns.

The cross-sectional area of the expanded PTFE article can be determinedby multiplying the width by the thickness at a given point along thelength.

In certain embodiments, the mean average cross-sectional area of theexpanded PTFE article along a given length can be at least 0.01 cm²,0.02 cm², or even at least 0.035 cm². In further embodiments, theexpanded PTFE article can have a mean average cross-sectional area ofthe expanded PTFE along a given length of no greater than 2 cm², nogreater than 1.5 cm², no greater than 1.4 cm², no greater than 1 cm², oreven no greater than 0.8 cm². In even further embodiments, the expandedPTFE article can have a mean average cross-section area of the expandedPTFE article along a given length in a range of any of the minimum andmaximum values described above, such as in a range of 0.01 cm² to 1.5cm², or even 0.035 cm² to 1.4 cm². It is to be understood that the meanaverage cross-sectional area of the expanded PTFE article is measuredbefore any cutting or trimming operation in the widthwise direction.

In certain embodiments, the expanded PTFE article described herein canhave an average specific gravity of at least 0.3, at least 0.4, or evenat least 0.5 along a length of the expanded PTFE article. In furtherembodiments, the expanded PTFE article described herein can have anaverage specific gravity of no greater than 2.5, no greater than 2.2, nogreater than 2.0, no greater than 1.9, or even no greater than 1.8, nogreater than 1.5, no greater than 1.3, or even no greater than 1.2. Inparticular embodiments, the expanded PTFE article can have an averagespecific gravity in a range of any of the minimum and maximum valuesdescribed above, such as in a range of 0.5 to 1.2.

In certain embodiments, the expanded PTFE article can have a particularporosity quantified by its Gurley Permeability. Gurley permeabilitymeasures the time for a volume of air to flow through a sheet ofmaterial. The Gurley tester is well known in the paper industry, and ahigher value indicates a less permeable sheet. In particularembodiments, an expanded PTFE article described herein can have anaverage Gurley Permeability of at least 10 seconds, at least 25 seconds,at least 50 seconds, at least 60 seconds, at least 70 seconds, at least75 seconds, at least 80 seconds, at least 85 seconds, or even at least90 seconds. In further embodiments, the expanded PTFE article describedherein can have an average Gurley Permeability of no greater than 500seconds, no greater than 200 seconds, or even no greater than 100seconds, or even no greater than 80 seconds. In particular embodiments,the expanded PTFE article described herein can have an average GurleyPermeability in a range of any of the minimum and maximum valuesdescribed above, such as in a range of 10 seconds to 80 seconds. Gurleypermeability measures the time for a volume of air to flow through asheet of material. The Gurley tester is well known in the paperindustry, and a higher value indicates a less permeable sheet.

One useful parameter to describe the quality of an expanded PTFE articleis its machine direction tensile stress at a maximum load, whichcharacterizes the expanded PTFE article's mechanical strength in themachine direction. The machine direction tensile stress at a maximumload is commonly used and understood by one of ordinary skill in theart. The values of the machine direction tensile stress at a maximumload described herein are measured with an Instron tensile tester inaccordance with ASTM-D882.

In certain embodiments, the machine direction tensile stress at amaximum load can be at least 1,900 psi, at least 2,100 psi, at least2,300 psi, or even at least 2,500 psi, at least 3,000 psi, or even atleast 4,000 psi. In further embodiments, the machine direction tensilestress at a maximum load can be no greater than 10,000 psi, no greaterthan 9,000 psi, or even no greater than 7,000 psi. In particularembodiments, the machine direction tensile stress at a maximum load canbe in a range of any of the minimum and maximum values described above,such as, in a range of 1,900 psi to 10,000 psi, 2,100 psi to 9,000 psi,or even 4,000 psi to 7,000 psi.

Another useful parameter to describe the quality of an expanded PTFEarticle is its cross-direction elongation to break, which characterizesthe expanded PTFE article's mechanical strength in the cross-machinedirection. The cross-direction elongation to break is commonly used andunderstood by one of ordinary skill in the art. The values of thecross-direction elongation to break described herein are measured withan Instron tensile tester in accordance with ASTM-D882.

In certain embodiments, the expanded PTFE article can have across-direction elongation to break of at least 500%, at least 600%, atleast 800%, at least 900%. In further embodiments, the PTFE article canhave a cross-direction elongation to break of no greater than about1000%. In particular embodiments, the PTFE article can have across-direction elongation to break in a range of any of the minimum andmaximum values described above, such as in a range of 600% to 1000%.

Another particular advantage of the present disclosure is the lowvariability of the cross-direction elongation to break at variouslocations across the width of the expanded PTFE article. For example, asdescribed in more detail herein, after extruding and finishing anexpanded PTFE article, the article is often cut lengthwise to generatemultiple articles having a smaller width than the original article.Thus, it is desired to have a consistency of the cross-directionelongation to break between the outer ends and the middle of theexpanded PTFE article so there is consistency between the multiple rollshaving a smaller width.

In certain embodiments, the expanded PTFE article described herein canhave a total variability between the outer ends and the middle of nogreater than 20%, no greater than 15%, no greater than 10%, or even nogreater than 5%. To measure the total variability of the cross-directionelongation to break, measurements are taken at the middle of the rollbefore cutting and at a point which is 10% of the total width from bothouter ends. The total variability of the cross-direction elongation tobreak can then be determined by subtracting the maximum from theminimum, dividing by the average, and multiplying by 100%.

Another useful parameter to describe the effectiveness of the expandedPTFE article described herein, particularly in a cable or wire assembly,is the dielectric constant and loss tangent of the expanded PTFEarticle, and even more particularly the variability of the dielectricconstant and loss tangent over a given length of the expanded PTFEarticle.

The dielectric constant (_(r)) of a PTFE article is a measure of thecapacitance of a construction using the PTFE article as a dielectric,compared to the capacitance of a similar construction in which thedielectric is a vacuum. The loss tangent (tan) of the PTFE article, alsocalled the dissipation factor, is a measure of the energy dissipated bythe PTFE article when in an oscillating electric field. Specifically, itis a determination of the degree to which the phase difference betweenthe current and the voltage of the charge motion generated in the PTFEarticle by an oscillating field in an adjacent conductor is shifted from90 degrees. It is expressed as the tangent of the angular phasedifference. The dielectric constant of the PTFE article employed as thedielectric material in a coaxial cable determines the speed at which anelectrical signal will travel in that coaxial cable. Signal propagationspeed is expressed relative to the speed of light in a vacuum, which isroughly 3.0×10¹⁰ cm/sec. The dielectric constant of a hard vacuum(space) is defined as 1.00. Higher dielectric constants will result inslower signal propagation speed. Loss tangent is a measure of how muchof the power of a signal is lost as it passes along a transmission lineon a dielectric material. Testing of the dielectric constant can beconducted at frequencies of 1 MHz and 20 GHz. At 1 MHz, the dielectricconstant can be measured according to the guidelines of ASTM D-150. Inparticular, the dielectric constant can be measured using aparallel-plate test fixture with 38 mm diameter electrodes. The electricfield can be linear and perpendicular to the plane of the samples. At 20GHz, testing can be conducted using the guidelines ofIPC-TM-650-2.5.5.13 Relative Permittivity and Loss Tangent Using aSplit=Cylinder Resonator in accordance with the guidelines of D2520-01.Results can be obtained using a split-cylinder cavity resonator andNational Institute of Standards and Technology (NIST) SplitC Version 1.0software. All measurements can be conducted under ambient conditions of25 degrees Celsius and 48% Relative Humidity (RH). Each test sample canbe comprised of two or more 2 inch by 2 inch pieces of film. Usingmulti-piece stacks can improve measurement accuracy.

In certain embodiments, an expanded PTFE article described herein canhave an average dielectric constant of no greater than 3, no greaterthan 2.7, no greater than 2.5, no greater than 2.3, no greater than 2.1,no greater than 1.9, no greater than 1.7, or even no greater than 1.5.Further, an expanded PTFE article described herein can have an averagedielectric constant of at least 0.5, at least 1, or even at least 1.3.In particular embodiments, an expanded PTFE article described herein canhave an average dielectric constant in a range of any of the minimum andmaximum values described above, such as in a range of 1 to 3.

Further, another useful measure of the performance of an expanded PTFEarticle described herein is the total dielectric constant variationalong a given length. To determine the total dielectric constantvariation along a given length, the dielectric constant is measured asdiscussed above at an interval of 5 meters over the specified length.The measurements are then analyzed to determine the minimum dielectricconstant and the maximum dielectric constant over the given length. Thetotal dielectric constant variation along a given length is thencalculated as the difference between the minimum and maximum dielectricconstant.

In certain embodiments, an expanded PTFE article described herein canhave a total dielectric constant variation of no greater than 1, nogreater than 0.8, no greater than 0.6, no greater than 0.5, no greaterthan 0.4, no greater than 0.3, no greater than 0.2, no greater than 0.1,or even no greater than 0.05. Further, an expanded PTFE articledescribed herein can have a total dielectric constant variation of atleast 0.005, or even no greater than 0.01. In particular embodiments, anexpanded PTFE article described herein can have a total dielectricconstant variation in a range of any of the minimum and maximum valuesdescribed above, such as in a range of 0.01 to 0.5.

In certain embodiments, the expanded PTFE article described herein canhave an average dielectric constant and/or a total dielectric constantvariation as recited above over a continuous length of at least 60meters, at least 100 meters, at least 250 meters, at least 320 meters,at least 500 meters, at least 750 meters, at least 1,000 meters, atleast 1,250 meters, at least 1,500 meters, at least 1,750 meters, oreven at least 2,000 meters. In particular embodiments, the expanded PTFEarticle described herein can have an average dielectric constant and/ora total dielectric constant variation as recited above over a continuouslength of at least 320 meters. In further embodiments, the expanded PTFEarticle described herein can have an average dielectric constant and/ora total dielectric constant variation as recited above over a continuouslength of no greater than 10,000 meters, no greater than 6,000 meters,or even no greater than 3,000 meters. In particular embodiments, theexpanded PTFE article can have an average dielectric constant and/or atotal dielectric constant variation as recited above over a continuouslength in a range of any of the minimum and maximum values describedabove, such as, 60 meters to 10,000 meters or even 320 meters to 6,000meters.

In certain embodiments, the expanded PTFE article described herein canhave an average loss tangent (dissipation factor (tan δ)) of no greaterthan 0.0003, no greater than 0.0002, no greater than 0.00013, no greaterthan 0.0001, no greater than 0.00005, no greater than 0.00002, or evenno greater than 0.00001, or even no greater than 0.000005. In furtherembodiments, the expanded PTFE article described herein can have anaverage loss tangent (dissipation factor (tan δ)) of at least 0.00000001or even at least 0.0000001. Moreover, the expanded PTFE articledescribed herein can have an average loss tangent (dissipation factor(tan δ)) in a range of any of the minimum and maximum values describedabove, such as in a range of 0.0000001 to 0.0002.

Further, another useful measure of the performance of an expanded PTFEarticle described herein is the loss tangent variation along a givenlength. To determine the loss tangent variation along a given length,the loss tangent is measured as discussed above at an interval of 5meters over the specified length. The measurements are then analyzed todetermine the minimum loss tangent and the maximum loss tangent over thegiven length. The loss tangent variation along a given length is thencalculated as the difference between the minimum and maximum losstangent, divided by the average loss tangent and multiplied by 100%.

In certain embodiments, the expanded PTFE article described herein canhave a loss tangent variation of no greater than 20%, no greater than10%, no greater than 8%, or even no greater than 5%, no greater than 3%,no greater than 2%, no greater than 1%, or even no greater than 0.1%.Further, in certain embodiments, the expanded PTFE article describedherein can have a loss tangent variation of at least 0.001%, at least0.01%, or even at least 0.1%. Moreover, in certain embodiments, theexpanded PTFE article described herein can have a loss tangent variationin a range of any of the minimum and maximum values described above,such as in a range of 0.01% to 8%, or even 0.1% to 5%. In certainembodiments, the expanded PTFE article described herein can have anaverage loss tangent and/or a loss tangent variation as recited aboveover a continuous length of at least 60 meters, at least 100 meters, atleast 250 meters, at least 320 meters, at least 500 meters, at least 750meters, at least 1,000 meters, at least 1,250 meters, at least 1,500meters, at least 1,750 meters, or even at least 2,000 meters. Inparticular embodiments, the expanded PTFE article described herein canhave an average loss tangent and/or a loss tangent variation as recitedabove over a continuous length of at least 320 meters. In furtherembodiments, the expanded PTFE article described herein can have anaverage loss tangent and/or a loss tangent variation as recited aboveover a continuous length of no greater than 10,000 meters, no greaterthan 6,000 meters, or even no greater than 3,000 meters. In particularembodiments, the expanded PTFE article can have an average loss tangentand/or a loss tangent variation as recited above over a continuouslength in a range of any of the minimum and maximum values describedabove, such as, 60 meters to 10,000 meters or even 320 meters to 6,000meters.

It is noted that the values of dielectric constant, dielectric constantvariation, loss tangent, and loss tangent variation described above, canbe obtained as measured in a low and/or high frequency of 1 MHz and 20GHz respectively.

Another aspect of the present disclosure is directed to a cable or wireassembly containing a PTFE article and/or an expanded PTFE articleaccording to any of the embodiments described above. The PTFE articleand/or the expanded PTFE article of the present disclosure may be usedto wrap an entire cable or wire or be used as an initial, intermediateand/or final wrap of the cable or wire.

Referring to FIG. 13, a cable assembly can include a transmission member1000 and an insulation member 1100 disposed around and covering thetransmission member 1000.

The transmission member 1000 can be constructed out of any materialcapable of allowing a signal to pass from a first end to a second end,opposite the first end. As illustrated in FIG. 13, there can be a singletransmission member 1000. In other embodiments, as illustrated in FIG.14, there can be a plurality of transmission members 1000. When there isa plurality of transmission members 1000, each transmission member 1000may be wrapped with an insulation member 1100 as will be discussed inmore detail below. Further, a second insulation member 1200 can bewrapped around the plurality of transmission members.

The insulation member 1100 can be wrapped around the transmission member1000 by any method in the art. For example, as illustrated in FIG. 13,the insulation member 1100 can be wrapped around the transmission memberin a spiral or helical fashion. In other embodiments, the insulationmember can be wrapped around the transmission member about its width. Asillustrated in FIG. 15, the insulation member 1100 can have a first edge1300 and a second edge 1400, opposite the first edge 1300. In veryparticular embodiments, when wrapped around the transmission member1000, the first edge 1300 of the insulation member 1100 can not overlapand even abut with the second edge 1400 of the insulation member andform a seam 1,500 along the length direction. In even further particularembodiments, a second insulation member 1600 can be wrapped around thefirst transmission member 1100. The second insulation member 1600 can bewrapped around the first transmission member 1000 in the same ordifferent fashion as the first transmission member. In even moreparticular embodiments, the seam 1700 of the second insulation membercan not align with, or in other words, can be spaced apart from the seam1,500 in the first insulation member. This way, it is ensured that thereis always a continuous layer of an insulation member about thecircumference of the transmission member.

In other embodiments, as illustrated in FIG. 13, the first edge of theinsulation member can overlap the second edge of the insulation member.

In certain embodiments, the cable or wire assembly can include more thanone insulation members, which can be the same or different. For example,referring again to FIG. 15, the cable or wire assembly can include afirst insulation member 1100 and a second insulation member 1600. Thesecond insulation member 1600 can be wrapped about the first insulationmember in a manner that staggers any seam formed by the insulationmembers.

In particular embodiments, any of the one or more insulation members orany other cable assembly can contain a PTFE article and/or expanded PTFEarticle described herein. The layering and wrapping can be configured inany manner useful for the desired cabling assembly.

EXAMPLES Example 1—Mix Time Analysis

Two different mixers were tested and compared for their mix time and mixuniformity. The two different mixers tested included Mixer 1—a standardcement mixer, which was the prior industry standard; and Mixer 2, whichdiffered from Mixer 1 in that it included 2 spray tips, a significantlyincreased volume capacity, an internal mechanism for intesification, andwas enclosed. For Mixer 2, 75 lbs of PTFE were loaded, and lubricant wasadded to achieve the target of 20% content of lubricant in the mixture.For Mixer 1, 30 lbs of PTFE were added, and lubricant was added toachieve the target of 20% content of lubricant in the mixture. It isnoted that the reduced amount of mixture in Mixer 1 was due to thecapacity limitations of the industry standard mixer. The mix time perpound for each mixture was held constant, and samples were evaluated atthe end of the mix cycle to determine the variation of lubricantconcentration between the samples.

A mixture was loaded into Mixer 1 and was mixed for 7 minutes. Threeseparate mixtures were loaded into Mixer 2 was mixed for 5 minutes, 8minutes, and 10 minutes respectively. After mixing, multiple samples ofeach mixture were tested to determine the mix uniformity, reported as adeviation from an average value of lubricant concentration. The resultsare reported in FIGS. 16 and 17. FIG. 16 illustrates an interval plot ofthe deviation from average lubricant concentration for Mixer 1 and thethree different mix times for Mixer 2. FIG. 17 illustrates a histogramof the deviation from average. As illustrated, the Mixer 2 demonstratedimproved mix uniformity, represented by a lower deviation from theaverage lubricant concentration.

Example 2—Lubricant Distribution after Incubation

As discussed above, a particular problem with increasing the size of abatch is the difficulty in maintaining a homogeneous distribution oflubricant after mixing and during incubation. The inventors discoveredthat when dealing with such large mixtures, vapor loss of the lubricantin the mixture can create significant variation in lubricantdistribution in the mixture after incubation.

Two large container assemblies having an interior capacity of about 17gallons were filled and tested to determine the % lubricant deviationfrom the original after incubation at 6 hours, 16 hours, and 6 days.

Container Assembly 1A—The first sample container assembly included abarrier structure containing a PVC disk and a flexible polymer sheetbetween the disk such that the PTFE and lubricant mixture had little tono air between the mixture and the flexible sheet.

Container Assembly 1B—The second sample container assembly was identicalto the first container assembly except that no barrier structure waspresent. The same amount of PTFE and lubricant was added to thecontainer assembly, and the container assembly was capped at its distalend, resulting in a significant air gap between the mixture and the cap.

Container Assembly 1B was stored for 6 hours, 16 hours, and 6 days.

Container Assembly 1A was stored for 16 hours, and the incubationprocedure was duplicated for 4 different samples.

Each Container Assembly was tested before capping for the % lubricantwithin the mixture. After each incubation time period, multiple sampleswere sequentially taken from the container assembly to see the deviationfrom the original % lubricant throughout the length of the containerassembly. The results are illustrated in FIGS. 18 and 19 which includeplots of the % lubricant deviation from the original and average atsequential samples throughout the length of the container assembly. FIG.18 illustrates the container assembly 1B, and FIG. 19 illustrates themultiple samples of container assembly 1A. As shown, use of the barrierstructure in the container assembly resulted in a more consistent anduniform lubricant distribution throughout the container assembly afterincubation.

Example 3—Final Tape Properties

Mechanical Properties

Three samples, 1A, 2A, and 3A were prepared according to one or moreembodiments of the disclosure and compared to commercially availablearticles formed from traditional processes using preform sizes havingabout 3 lbs of PTFE (samples 1B, 2B, and 3B). In particular, samples 1A,2A, and 3A were formed in a process as generally outlined in FIG. 1. Inparticular, 100 parts of PTFE powder was mixed with 20 parts of Isopar.The total mixture included 75 lbs of PTFE. The mixture was mixed in aMixer 2, as detailed in Example 1 above. After incubation, the mixturewas then transferred into the preform. The mixture was compressed in thepreform at a compaction force of about 300 psi. The preform was thenrotated into position above the die. Once in position, the compactedmixture was paste extruded through a die. All samples were thencalendared, dried, and wound as illustrated in the set up of FIG. 1,with standard adjustments for the various thickness and specific gravitytargets. Sample 1A included the same formulation and target thickness asSample 1B. Sample 2A included the same formulation and target thicknessas Sample 2B. Sample 3A included the same formulation and targetthickness as Sample 3B.

Sample 1B—is a commercially available PTFE article from Saint-Gobainunder the designation NORTON® R128. This article was constructed from aprocess which uses preforms of about 3 lbs of PTFE. The thickness targetwas 3 mil.

Sample 2B—is a commercially available PTFE article from Saint-Gobainunder the designation NORTON® R141. This article was constructed from aprocess which uses preforms of about 3 lbs of PTFE. The thickness targetwas 3.5 mil.

Sample 3B—is a commercially available PTFE article from Saint-Gobainunder the designation NORTON® R142. This article was constructed from aprocess which uses preforms of about 3 lbs of PTFE. The thickness targetwas 2.0 mil.

All samples were then tested and compared for their mechanicalproperties and dimensional tolerances. All property measurements wereconducted according to the testing methods described above.

TABLE 2 Performance Properties - values are average ± 1 standarddeviation. MD Tensile MD Tensile CD Tensile CD Tensile Gurley Stress atMax Strain at Max Stress at Max Strain at Break Sample (seconds) Load(psi) Load (%) Load (psi) (%) 1A 80.7 ± 2.9 2633 ± 44 32.6 ± 2.5 200 ±12 956 ± 69  1B 52.1 ± 0.9 1870 ± 64 72.2 ± 7.6 203 ± 18 796 ± 63  2A89.3 ± 4.3 2479 ± 81 34.8 ± 3.5 199 ± 15 1000 ± 1   2B 60.9 ± 4.0 1639 ±77  62.8 ± 17.7 200 ± 41 516 ± 166 3A 109.8 ± 34.2  4384 ± 118 13.7 ±0.9 268 ± 17 917 ± 113 3B N/A  2962 ± 301 48.1 ± 3.7 279 ± 19 630 ± 116

Tensile Properties CD Uniformity

Samples 1A, 1B, 2A, and 2B were further tested for various mechanicaland dimension property uniformity. In particular, the samples weretested for their cross direction tensile stress variation at the center,operator side and drive side of the PTFE article. The results areillustrated in FIGS. 20-21. FIG. 20 corresponds to samples 1A and 1B,and FIG. 21 corresponds to samples 2A and 2B. As shown, there issignificantly less variability of the tensile properties across thewidth of the PTFE article.

Thickness Variation

Sample 4A was prepared like Sample 1A, except with a thickness target of63 microns (2.5 mil). Sample 4B was prepared like Sample 4A, except witha thickness target of 88 microns (3.1 mil). Sample 4C was commerciallyavailable from Saint-Gobain under the designation NORTON® R137, and athickness target of 50 microns (2 mil). Sample 4C was produced from aprocess in which the preform of about 3 lbs of PTFE. Each sample wastested for its thickness variation across its length. The thickness wasmeasured by a shadowcasting technique at intervals of 10 measurementsper second with a line speed varying between 90 and 200 feet per minute.The results are illustrated in FIGS. 22-24, with FIG. 22 illustratingthe thickness variation of two articles of sample 4A, FIG. 23illustrating the thickness variation of two articles of sample 4B, andFIG. 24 illustrating the thickness variation of sample 4C. Further, theaverage plus or minus the standard deviation for samples 4A-4C areprovided in Table 3 below.

TABLE 3 Average Thickness and Standard Deviation of Samples 4A-4C Sample4A Sample 4B Sample 4C Average Thickness 63.0 88.5 49.2 (microns)Standard Deviation 0.838 0.989 2.36

As shown, the PTFE article of Samples 4A and 4B illustratessignificantly improved thickness variation across the entire length. Itis particularly noted that the large spikes shown in the measurementsfor Sample 4C correspond to the presence of a joint from the successiveextrusion of small preforms.

Example 4—Experiments Showing Improvement in an Expanded PTFE Article

Sample 5A—The article of sample 1A was expanded to obtain a 6 mil targetfinished article having a specific gravity target of 0.7.

Sample 5B—The expanded PTFE article commercially available fromSaint-Gobain under the designation Norton® R167. This article was madefrom a process incorporating a preform which could only hold about 3 lbsof PTFE.

Samples 5A and 5B were tested for their dimensional and mechanicalproperties, and particularly the variability of those propertiesthroughout the length of the article.

Machine Direction Tensile Strength

Samples 5A and 5B were measured for their machine direction tensilestrength as described above. The results are illustrated in FIG. 25. Asillustrated, Sample 5A shows a significantly higher machine directiontensile strength indicating that the higher values observed beforeexpansion and illustrated in the Examples above also translated to thefinished expanded material.

Machine Direction Elongation

Samples 5A and 5B were measured for their machine direction elongationas described above. The results are illustrated in FIG. 26. Asillustrated, Sample 5A shows a significantly lower machine directionelongation than Sample 5B.

Cross Direction Tensile Strength

Samples 5A and 5B were measured for their cross direction tensilestrength as described above. The results are illustrated in FIG. 27. Asillustrated, Sample 5A shows a higher average cross direction tensilestrength and a lower variation of cross direction tensile strength.

Specific Gravity

Samples 5A and 5B were measured for their specific gravity as describedabove. The results are illustrated in FIG. 28.

Variability Over the Length

Sample 5A was measured for its variation in machine direction tensilestrength, machine direction elongation, specific gravity, and thickness.As described above, during production, the target was a 6 millimeterthickness and a specific gravity of 0.7. To measure the variability ofthe properties described above, measurements were taken off a single,monolithic article at 10 different positions across the length, spaced30 yards apart. The total length of the article measured was about 300yards. The results are illustrated in FIGS. 29-32. As illustrated,Sample 5A shows a high average cross-direction tensile strength and alow variation of cross direction tensile strength among the 10 differentmeasurements throughout the length. Further, the sample 5A shows a verylow variability of thickness and specific gravity throughout the length.

Many different aspects and embodiments are possible. Some of thoseaspects and embodiments are described below. After reading thisspecification, skilled artisans will appreciate that those aspects andembodiments are only illustrative and do not limit the scope of thepresent invention. Embodiments may be in accordance with any one or moreof the items as listed below.

Item 1. A cable or wire assembly, the cable comprising: a transmissionmember, having a first end and a second end spaced apart from the firstend, wherein the transmission member is adapted to pass a signal fromthe first end of the transmission member to the second end of thetransmission member; an insulation member disposed around and coveringthe transmission member, wherein the insulation member comprises PTFE;and wherein the insulation member has a total thickness variation of nogreater than 20 microns over a length of at least 80 meters.

Item 2. A cable or wire assembly, comprising: a transmission member,having a first end and a second end spaced apart from the first end,wherein the transmission member is adapted to pass a signal from thefirst end of the transmission member to the second end of thetransmission member; an insulation member disposed around and coveringthe transmission member, wherein the insulation member comprises PTFE;and wherein the insulation member has a Total Dielectric ConstantVariation of no greater than 0.5, measured at 1 MHz.

Item 3. A cable or wire assembly, comprising: a transmission member,having a first end and a second end spaced apart from the first end,wherein the transmission member is adapted to pass a signal from thefirst end of the transmission member to the second end of thetransmission member; an insulation member disposed around and coveringthe transmission member, wherein the insulation member comprises PTFE;and wherein the insulation member is essentially joint free over acontinuous length of at least 80 meters.

Item 4. The cable or wire assembly of any one of the preceding items,wherein the insulation member is wrapped helically around thetransmission member.

Item 5. The cable or wire assembly of any one of the preceding items,wherein the cable or wire assembly comprises a first insulation memberwrapped around the transmission member, and a second insulation memberwrapped around the first insulation member.

Item 6. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a first edge along the lengthdirection and a second edge along the length direction, opposite thefirst edge, wherein the insulation member is wrapped around thetransmission member, and wherein the first edge does not overlap thesecond edge.

Item 7. The cable or wire assembly of any one of the preceding items,wherein the cable comprises a plurality of insulation members, andwherein at least two of the plurality of insulation members is wrappedaround the one or more transmission members.

Item 8. The cable or wire assembly of any one of the preceding items,wherein the cable comprises a first insulation member and a secondinsulation member, and the first insulation member is wrapped around thetransmission member, and wherein the second insulation member is wrappedaround the first insulation member, wherein the first and secondinsulation members have a first edge along the length direction and asecond edge along the length direction, opposite the first edge.

Item 9. The cable or wire assembly of any one of the preceding items,wherein the cable or wire assembly is in the form of a coaxial cable.

Item 10. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a first edge along the lengthdirection and a second edge along the length direction, opposite thefirst edge, wherein at least one of the one or more insulation member iswrapped around the one or more transmission members, and wherein thefirst edge overlaps the second edge.

Item 11. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a Total Dielectric Constant Variationof no greater than 1, no greater than 0.8, no greater than 0.6, nogreater than 0.5, no greater than 0.4, no greater than 0.3, no greaterthan 0.2, no greater than 0.1, or even no greater than 0.05, measured at1 MHz.

Item 12. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a Total Dielectric Constant Variationof no greater than 1, no greater than 0.8, no greater than 0.6, nogreater than 0.5, no greater than 0.4, no greater than 0.3, no greaterthan 0.2, no greater than 0.1, or even no greater than 0.05, measured at20 GHz.

Item 13. The cable or wire assembly of any one of the preceding items,wherein the insulation member has no more than 5 joints, no more than 4joints, no more than 3 joints, no more than 2 joints, no more than 1joint, or is even essentially joint free.

Item 14. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a continuous length of at least 60meters, at least 100 meters, at least 250 meters, at least 320 meters,at least 500 meters, at least 750 meters, at least 1,000 meters, atleast 1,250 meters, at least 1,500 meters, at least 1,750 meters, oreven at least 2,000 meters.

Item 15. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a continuous length of at least 60meters, at least 100 meters, at least 250 meters, at least 320 meters,at least 500 meters, at least 750 meters, at least 1,000 meters, atleast 1,250 meters, at least 1,500 meters, at least 1,750 meters, oreven at least 2,000 meters; and wherein the PTFE article has no morethan 5 joints, no more than 4 joints, no more than 3 joints, no morethan 2 joints, no more than 1 joint, or is even essentially joint free.

Item 16. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a continuous length of at least 320meters and is essentially joint free.

Item 17. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a total thickness variation of nogreater than 20 microns, no greater than 18 microns, no greater than 16microns, no greater than 14 microns, no greater than 12 microns, nogreater than 10 microns, no greater than 8 microns, no greater than 7microns, or even no greater than 5 microns.

Item 18. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a total thickness variation of atleast 0.1 microns, at least 1 micron, or even at least 2 microns.

Item 19. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a total thickness variation in a rangeof 0.1 microns to 20 microns, 1 micron to 16 microns, or even 2 micronsto 10 microns.

Item 20. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a total thickness variation of nogreater than 20 microns, no greater than 18 microns, no greater than 16microns, no greater than 14 microns, no greater than 12 microns, nogreater than 10 microns, no greater than 8 microns, no greater than 7microns, or even no greater than 5 microns; and wherein the insulationmember has the specified total thickness variation across a continuouslength of 60 meters, 100 meters, 250 meters, 320 meters, 500 meters, 750meters, 1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even2,000 meters.

Item 21. The cable or wire assembly of any one of the preceding items,wherein the insulation member comprises expanded PTFE.

Item 22. The cable or wire assembly of any one of the preceding items,wherein the cable or wire comprises a first insulation member and asecond insulation member, wherein the first insulation member isdisposed nearer to the transmission member than the second insulationmember; and wherein the first insulation member has a specific gravitythat is greater than a specific gravity of the second insulation member.

Item 23. The cable or wire assembly of any one of the preceding items,wherein the insulation member has an average loss tangent (dissipationfactor (tan δ)) of no greater than 0.0003, no greater than 0.0002, nogreater than 0.00013, no greater than 0.0001, no greater than 0.00005,no greater than 0.00002, or even no greater than 0.00001, or even nogreater than 0.000005.

Item 24. The cable or wire assembly of any one of the preceding items,wherein the insulation member has an average loss tangent (dissipationfactor (tan δ)) in a range of any of the minimum and maximum valuesdescribed above, such as in a range of 0.0000001 to 0.0002.

Item 25. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a loss tangent variation of no greaterthan 20%, no greater than 10%, no greater than 8%, or even no greaterthan 5%, no greater than 3%, no greater than 2%, no greater than 1%, oreven no greater than 0.1%.

Item 26. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a standard deviation of averagethickness of no more than 2.3, no more than 2.2, no more than 2.1, nomore than 2.0, no more than 1.9, no more than 1.8, no more than 1.7, nomore than 1.6, no more than 1.5, no more than 1.4, no more than 1.3, nomore than 1.2, no more than 1.1, no more than 1, or even no more than0.9 over a continuous length of 60 meters, 100 meters, 250 meters, 320meters, 500 meters, 750 meters, 1,000 meters, 1,250 meters, 1,500meters, 1,750 meters, or even 2,000 meters.

Item 27. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a standard deviation of averagethickness of less than 2.3 over a continuous length of 80 meters.

Item 28. The cable or wire assembly of any one of the preceding items,wherein the insulation member has a standard deviation of averagethickness of less than 1.5 over a continuous length of 320 meters.

Item 29. An article comprising Polytetrafluoroethylene (PTFE), thearticle having a continuous length of at least 80 meters, and whereinthe article is essentially joint free over a continuous length of 80meters.

Item 30. An article comprising PTFE, the article having a continuouslength of at least 80 meters, and wherein the article has a mean averagethickness of less than 125 microns, and wherein the article is jointfree over a continuous length of 80 meters.

Item 31. An article comprising PTFE, the article having a continuouslength of at least 80 meters, wherein the article has a total thicknessvariation (TTV) of less than 20 microns over a continuous length of 80meters, and wherein the article has a mean average thickness of lessthan 250 microns.

Item 32. An article comprising PTFE, the article having a continuouslength of at least 80 meters, wherein the article has a % thicknessvariation of less than 20% over a continuous length of 80 meters, andwherein the article has a mean average thickness of less than 80microns.

Item 33. An article comprising PTFE, the article having a continuouslength of at least 80 meters, wherein the article has a % thicknessvariation of less than 15% over a continuous length of 80 meters, andwherein the article has a mean average thickness of less than 250microns.

Item 34. An article comprising PTFE, the article having a continuouslength of at least 80 meters, wherein the article has a % thicknessvariation of no greater than 10% over a continuous length of 80 meters,and wherein the article has a mean average thickness of less than 80microns.

Item 35. An article comprising PTFE, wherein the article has a machinedirection tensile stress at a max load of greater than 1,900 psi.

Item 36. An article comprising PTFE, wherein the article has acontinuous length of at least 80 meters, and wherein the article has anaverage Gurley Permeability of at least 50 seconds across a continuouslength of 80 meters.

Item 37. The article according to any one of the preceding items,wherein the PTFE article has no more than 5 joints, no more than 4joints, no more than 3 joints, no more than 2 joints, no more than 1joint, or is even essentially joint free.

Item 38. The article according to any one of the preceding items,wherein the PTFE article has a continuous length of at least 60 meters,at least 100 meters, at least 250 meters, at least 320 meters, at least500 meters, at least 750 meters, at least 1,000 meters, at least 1,250meters, at least 1,500 meters, at least 1,750 meters, or even at least2,000 meters.

Item 39. The article according to any one of the preceding items,wherein the PTFE article has no more than 5 joints, no more than 4joints, no more than 3 joints, no more than 2 joints, no more than 1joint, or is even essentially joint free over a continuous length of 60meters, 100 meters, 250 meters, 320 meters, 500 meters, 750 meters,1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even 2,000meters.

Item 40. The article according to any one of the preceding items,wherein the article has no more than 5 joints over a continuous lengthof 500 meters.

Item 41. The article according to any one of the preceding items,wherein the article has no more than 4 joints over a continuous lengthof 320 meters.

Item 42. The article according to any one of the preceding items,wherein the article has no more than 3 joints over a continuous lengthof 250 meters.

Item 43. The article according to any one of the preceding items,wherein the article has a continuous length of at least 320 meters, andis essentially joint free over a continuous length of 320 meters.

Item 44. The article according to any one of the preceding items,wherein the article has a total thickness variation of no greater than20 microns, no greater than 18 microns, no greater than 16 microns, nogreater than 14 microns, no greater than 12 microns, no greater than 10microns, no greater than 8 microns, no greater than 7 microns, or evenno greater than 5 microns over a continuous length of 80 meters.

Item 45. The article according to any one of the preceding items,wherein the article has a total thickness variation of at least 0.1microns, at least 1 micron, or even at least 2 microns over a continuouslength of 80 meters.

Item 46. The article according to any one of the preceding items,wherein the article has a total thickness variation in a range of 0.1microns to 20 microns, 1 micron to 16 microns, or even 2 microns to 10microns over a continuous length of 80 meters.

Item 47. The article according to any one of the preceding items,wherein the article has a total thickness variation of no greater than20 microns, no greater than 18 microns, no greater than 16 microns, nogreater than 14 microns, no greater than 12 microns, no greater than 10microns, no greater than 8 microns, no greater than 7 microns, or evenno greater than 5 microns over a continuous length of 60 meters, 100meters, 250 meters, 320 meters, 500 meters, 750 meters, 1,000 meters,1,250 meters, 1,500 meters, 1,750 meters, or even 2,000 meters.

Item 48. The article according to any one of the preceding items,wherein the article has a total thickness variation of no greater than20 microns over a continuous length of 80 meters.

Item 49. The article according to any one of the preceding items,wherein the article has a total thickness variation of no greater than20 microns over a continuous length of 100 meters.

Item 50. The article according to any one of the preceding items,wherein the article has a total thickness variation of no greater than20 microns over a continuous length of 250 meters.

Item 51. The article according to any one of the preceding items,wherein the article has a total thickness variation of no greater than20 microns over a continuous length of 500 meters.

Item 52. The article according to any one of the preceding items,wherein the article has a total thickness variation of no greater than20 microns over a continuous length of 2,000 meters.

Item 53. The article according to any one of the preceding items,wherein the article, has a mean average thickness of no greater than1000 microns, no greater than 500 microns, no greater than 250 microns,no greater than 200 microns, no greater than 150 microns, no greaterthan 125 microns, no greater than 100 microns, no greater than 75microns, or even no greater than 60 microns over a continuous length of80 meters; and/or a mean average thickness of at least 0.1 microns, atleast 1 micron, at least 5 microns, at least 10 microns, at least 20microns, at least 30 microns, or even at least 40 microns over acontinuous length of 80 meters.

Item 54. The article according to any one of the preceding items,wherein the article has a width, and a length, and wherein the length isgreater than the width, wherein the length is in a machine direction,and wherein the width is in a cross machine direction.

Item 55. The article according to any one of the preceding items,wherein the article has an average, uncut width, of at least 0.001meters, at least 0.01 meters, at least 0.1 meters or even at least 0.2meters; an average, uncut width, of no greater than 2 meters, no greaterthan 1 meter, or even no greater than 0.5 meters; or an average, uncutwidth, in a range of 0.001 meters to 2 meters, or even 0.2 meters to 0.5meters.

Item 56. The article according to any one of the preceding items,wherein the article has a machine direction tensile stress at a max loadof greater than 1,900 psi, greater than 2,100 psi, greater than 2,300psi, or greater than 2,500 psi as measured according to ASTM-D882.

Item 57. The article according to any one of the preceding items,wherein the article has a machine direction tensile stress at a max loadof greater than 2,300 psi as measured according to ASTM-D882.

Item 58. The article according to any one of the preceding items,wherein the article has a machine direction tensile stress at a max loadof greater than 2400 psi as measured according to ASTM-D882.

Item 59. The article according to any one of the preceding items,wherein the article has a cross direction elongation to break of atleast 600%, or even at least 900% as measured according to ASTM-D882.

Item 60. The article according to any one of the preceding items,wherein the article has a cross direction tensile stress that varies byno more than 20% between the center and edges.

Item 61. The article according to any one of the preceding items,wherein the article has an average specific gravity of at least 1.4, atleast 1.45, at least 1.51, or even at least 1.6.

Item 62. The article according to any one of the preceding items,wherein the article has an average specific gravity of no greater than2.5, no greater than 2.2, no greater than 2.0, no greater than 1.9, nogreater than 1.8.

Item 63. The article according to any one of the preceding items,wherein the article has an average Gurley Permeability of at least 50seconds, at least 60 seconds, at least 70 seconds, at least 75 seconds,at least 80 seconds, at least 85 seconds, or even at least 90 seconds.

Item 64. The article according to any one of the preceding items,wherein the article is laser markable.

Item 65. The article according to any one of the preceding items,wherein the article is in the form of a roll.

Item 66. The article according to any one of the preceding items,wherein the PTFE comprises a PTFE homopolymer, a PTFE copolymer, orcombinations thereof.

Item 67. The article according to any one of the preceding items,wherein the article comprises a photosensitive material.

Item 68. The article according to any one of the preceding items,wherein the article comprises a photosensitive material, and wherein thephotosensitive material comprises a metal oxide.

Item 69. The article according to any one of the preceding items,wherein the article comprises an oxide, and wherein the oxide comprisesSnO₂, ZnO, AZO, TiO₂, CeO₂, Nb₂O₅, MoO₃, WO₃, V₂O₅, Cr₂O₃, Fe₂O₃, NiO,CuO, CdO and Tl₂O₃.

Item 70. The article according to any one of the preceding items,wherein the article comprises a photosensitive material in an amount ofat least about 0.1%, at least about 0.5%, or even at least about 1% byweight, based on the weight of the PTFE.

Item 71. The article according to any one of the preceding items,wherein the article comprises a photosensitive material in an amount ofno greater than 20%, no greater than 10%, or even no greater than about5% by weight, based on the weight of the PTFE.

Item 72. The article according to any one of the preceding items,wherein the article has an average loss tangent (dissipation factor (tanδ)) of no greater than 0.0003, no greater than 0.0002, no greater than0.00013, no greater than 0.0001, no greater than 0.00005, no greaterthan 0.00002, or even no greater than 0.00001, or even no greater than0.000005.

Item 73. The article according to any one of the preceding items,wherein the article has an average loss tangent (dissipation factor (tanδ)) in a range of any of the minimum and maximum values described above,such as in a range of 0.0000001 to 0.0002.

Item 74. The article according to any one of the preceding items,wherein the article has a loss tangent variation of no greater than 20%,no greater than 10%, no greater than 8%, or even no greater than 5%, nogreater than 3%, no greater than 2%, no greater than 1%, or even nogreater than 0.1%.

Item 75. The article according to any one of the preceding items,wherein the article has a standard deviation of average thickness of nomore than 2.3 microns, no more than 2.2 microns, no more than 2.1microns, no more than 2.0 microns, no more than 1.9 microns, no morethan 1.8 microns, no more than 1.7 microns, no more than 1.6 microns, nomore than 1.5 microns, no more than 1.4 microns, no more than 1.3microns, no more than 1.2 microns, no more than 1.1 microns, no morethan 1 micron, or even no more than 0.9 microns over a continuous lengthof 60 meters, 100 meters, 250 meters, 320 meters, 500 meters, 750meters, 1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even2,000 meters.

Item 76. The article according to any one of the preceding items,wherein the article has a standard deviation of average thickness ofless than 2.3 microns over a continuous length of 80 meters.

Item 77. The article according to any one of the preceding items,wherein the article has a standard deviation of average thickness ofless than 1.5 microns over a continuous length of 320 meters.

Item 78. The article according to any one of the preceding items,wherein the article is in the form of a film.

Item 79. The article according to any one of the preceding items,wherein the article is in the form of a tape.

Item 80. The article according to any one of the preceding items,wherein the article further comprises a transmission member, and aninsulation member, and wherein the insulation member is wrapped aroundthe transmission member, and wherein the PTFE is contained in theinsulation member.

Item 81. A wire or cable assembly comprising the article according toany one of the preceding items.

Item 82. An expanded article comprising PTFE, wherein the article has acontinuous length of at least 80 meters, and wherein the expanded PTFEarticle is essentially joint free.

Item 83. An expanded article comprising PTFE, wherein the article has acontinuous length of at least 80 meters, and a total thickness variationof less than 20 microns over a continuous length of 80 meters.

Item 84. An expanded article comprising PTFE, the article having acontinuous length of at least 80 meters, wherein the article has a totalthickness variation (TTV) of less than 20 microns over a continuouslength of 80 meters, and wherein the article has a mean averagethickness of less than 250 microns.

Item 85. An expanded article comprising PTFE, the article having acontinuous length of at least 80 meters, wherein the article has a %thickness variation of less than 20% over a continuous length of 80meters, and wherein the article has a mean average thickness of lessthan 80 microns.

Item 86. An expanded article comprising PTFE, the article having acontinuous length of at least 80 meters, wherein the article has a %thickness variation of less than 15% over a continuous length of 80meters, and wherein the article has a mean average thickness of lessthan 250 microns.

Item 87. An expanded article comprising PTFE, the article having acontinuous length of at least 80 meters, wherein the article has a %thickness variation of no greater than 10% over a continuous length of80 meters, and wherein the article has a mean average thickness of lessthan 80 microns.

Item 88. The expanded article according to any one of the precedingitems, wherein the expanded PTFE article has no more than 5 joints, nomore than 4 joints, no more than 3 joints, no more than 2 joints, nomore than 1 joint, or is even essentially joint free.

Item 89. The expanded article according to any one of the precedingitems, wherein the PTFE article has a continuous length of at least 60meters, at least 100 meters, at least 250 meters, at least 320 meters,at least 500 meters, at least 750 meters, at least 1,000 meters, atleast 1,250 meters, at least 1,500 meters, at least 1,750 meters, oreven at least 2,000 meters.

Item 90. The expanded article according to any one of the precedingitems, wherein the PTFE article has a continuous length of at least 60meters, at least 100 meters, at least 250 meters, at least 320 meters,at least 500 meters, at least 750 meters, at least 1,000 meters, atleast 1,250 meters, at least 1,500 meters, at least 1,750 meters, oreven at least 2,000 meters; and wherein the PTFE article has no morethan 5 joints, no more than 4 joints, no more than 3 joints, no morethan 2 joints, no more than 1 joint, or is even essentially joint free.

Item 91. The expanded article according to any one of the precedingitems, wherein the expanded article has a total thickness variation ofno greater than 20 microns, no greater than 18 microns, no greater than16 microns, no greater than 14 microns, no greater than 12 microns, nogreater than 10 microns, no greater than 8 microns, no greater than 7microns, or even no greater than 5 microns.

Item 92. The expanded article according to any one of the precedingitems, wherein the expanded article has a total thickness variation ofat least 0.1 microns, at least 1 micron, or even at least 2 microns.

Item 93. The expanded article according to any one of the precedingitems, wherein the expanded article has a total thickness variation in arange of 0.1 microns to 20 microns, 1 micron to 16 microns, or even 2microns to 10 microns.

Item 94. The expanded article according to any one of the precedingitems, wherein the expanded article has a total thickness variation ofno greater than 20 microns, no greater than 18 microns, no greater than16 microns, no greater than 14 microns, no greater than 12 microns, nogreater than 10 microns, no greater than 8 microns, no greater than 7microns, or even no greater than 5 microns; and wherein the expandedarticle has the specified total thickness variation across a continuouslength of 60 meters, 100 meters, 250 meters, 320 meters, 500 meters, 750meters, 1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even2,000 meters

Item 95. The expanded article of any one of the preceding items, whereinthe expanded PTFE article, has an average thickness of no greater than1000 microns, no greater than 500 microns, no greater than 250 microns,no greater than 200 microns, no greater than 150 microns, no greaterthan 125 microns, no greater than 100 microns, no greater than 75microns, or even no greater than 60 microns; and/or an average thicknessof at least 0.1 microns, at least 1 micron, at least 5 microns, at least10 microns, at least 20 microns, at least 30 microns, or even at least40 microns.

Item 96. The expanded PTFE article of any one of the preceding items,wherein the expanded PTFE article has a specific gravity of at least0.1, at least 0.3, or even at least 0.5.

Item 97. The expanded article of any one of the preceding items, whereinthe expanded article has a specific gravity of no greater than 1.5, nogreater than 1.3, no greater than 1.2, or even no greater than 1.1.

Item 98. The expanded article of any one of the preceding items, whereinthe expanded article has a specific gravity in a range of 0.1 to 1.5,0.3 to 1.3, or even 0.5 to 1.2.

Item 99. The expanded article of any one of the preceding items, whereinthe expanded article has a machine direction tensile strength of atleast 3,000 psi, at least 3,500 psi, at least 4,000 psi, at least 4,200psi, or even at least 4,400 psi.

Item 100. The expanded article of any one of the preceding items,wherein the expanded article has a machine direction tensile strength ofno greater than 10,000 psi, no greater than 9,000 psi, or even nogreater than 7,000 psi.

Item 101. The expanded article of any one of the preceding items,wherein the expanded article has a machine direction tensile strength ina range of 3,000 psi to 10,000 psi, 3,500 psi to 9,000 psi, or even4,000 psi to 8000 psi.

Item 102. The expanded article according to any one of the precedingitems, wherein the PTFE comprises a PTFE homopolymer, a PTFE copolymer,or combinations thereof.

Item 103. The expanded article according to any one of the precedingitems, wherein the article comprises a photosensitive material.

Item 104. The expanded article according to any one of the precedingitems, wherein the article comprises a photosensitive material, andwherein the photosensitive material comprises a metal oxide.

Item 105. The expanded article according to any one of the precedingitems, wherein the article comprises a metal oxide, and wherein themetal oxide comprises SnO₂, ZnO, AZO, TiO₂, CeO₂, Nb₂O₅, MoO₃, WO₃,V₂O₅, Cr₂O₃, Fe₂O₃, NiO, CuO, CdO, Tl₂O₃, or combinations thereof.

Item 106. The expanded article according to any one of the precedingitems, wherein the article comprises a photosensitive material in anamount of at least about 0.1%, at least about 0.5%, or even at leastabout 1% by weight, based on the weight of the PTFE.

Item 107. The expanded article according to any one of the precedingitems, wherein the article comprises a photosensitive material in anamount of no greater than 20%, no greater than 10%, or even no greaterthan about 5% by weight, based on the weight of the PTFE.

Item 108. The expanded article of any one of the preceding items,wherein the expanded article has a standard deviation of averagethickness of no more than 2.3 microns, no more than 2.2 microns, no morethan 2.1 microns, no more than 2.0 microns, no more than 1.9 microns, nomore than 1.8 microns, no more than 1.7 microns, no more than 1.6microns, no more than 1.5 microns, no more than 1.4 microns, no morethan 1.3 microns, no more than 1.2 microns, no more than 1.1 microns, nomore than 1 micron, or even no more than 0.9 microns over a continuouslength of 60 meters, 100 meters, 250 meters, 320 meters, 500 meters, 750meters, 1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even2,000 meters.

Item 109. The expanded article of any one of the preceding items,wherein the expanded article has a standard deviation of averagethickness of less than 2.3 microns over a continuous length of 80meters.

Item 110. The expanded article of any one of the preceding items,wherein the expanded article has a standard deviation of averagethickness of less than 1.5 microns over a continuous length of 320meters.

Item 111. A method for producing an article comprising PTFE, the methodcomprising: mixing materials comprising PTFE and a lubricant to form amixture; providing a preform tube; loading the preform tube with themixture; compacting the mixture within the preform tube; positioning thepreform tube into communication with a die; and extruding the mixturefrom the preform tube through the die; wherein the mixture comprises atleast 4 lbs of the PTFE.

Item 112. A method for producing an article comprising PTFE, the methodcomprising: mixing materials comprising PTFE and a lubricant to form amixture; providing a preform tube; loading the preform tube with themixture; compacting the mixture within the preform tube; positioning thepreform tube into communication with a die; and extruding the mixturefrom the preform tube through the die; wherein the article extruded froma single preform tube has a length of at least 80 meters.

Item 113. A method for producing an article comprising PTFE, the methodcomprising: mixing materials comprising PTFE and a lubricant to form amixture; providing a preform tube; loading the preform tube with themixture; compacting the mixture within the preform tube; positioning thepreform tube into communication with a die; and extruding the mixturefrom the preform tube through the die; wherein the article has a lengthof at least 80 meters, and wherein the article is essentially joint freeover a continuous length of 80 meters.

Item 114. A method for producing an article comprising PTFE, the methodcomprising: mixing materials comprising PTFE and a lubricant to form amixture; providing a preform tube; loading the preform tube with themixture; compacting the mixture within the preform tube; positioning thepreform tube into communication with a die; and extruding the mixturefrom the preform tube through the die; wherein essentially all of themixture that is loaded into a single preform tube is mixed together in asingle batch, and wherein the single batch comprises at least 25 lbs ofPTFE.

Item 115. A method for producing an article comprising PTFE, the methodcomprising: providing a preform tube, wherein the preform tube has aninternal cross-sectional area; loading the preform tube with a mixturecomprising PTFE and a lubricant; compacting the mixture within thepreform tube; extruding the mixture from the preform tube, wherein thearticle has a cross-sectional area immediately after extrusion; andwherein a reduction ratio of a cross-sectional area of the preform tubeto the narrowest cross-sectional area of the die is at least 50.

Item 116. A method for producing an article comprising PTFE, the methodcomprising: providing a preform tube having a first end having a firstopening and a second end having a second opening; loading a mixturecomprising PTFE and lubricant into the preform tube, wherein, duringloading, the first opening of the preform tube is disposed at a lowerelevation than the second opening of the preform tube, and wherein,during loading, the first opening is covered; actively compacting themixture from the first end; and actively compacting the mixture from thesecond end.

Item 117. A method for producing an article comprising PTFE, the methodcomprising: providing a preform tube; loading the preform tube with amixture comprising PTFE and a lubricant; compacting the mixture withinthe preform tube; extruding the mixture from the preform tube to form anarticle, winding the article to form a roll, and cutting one or bothwidth ends of the roll so that the wound roll has an average widthvariation of less than about 1%, and wherein the roll has a widthwiseyield loss of less than about 20 percent.

Item 118. The method of any one of the preceding items, wherein themixture comprises at least 5, at least 7, at least 10, at least 12, atleast 15, at least 17, at least 20, at least 25, at least 30, at least35, at least 40, at least 45, at least 50, at least 55, at least 60, atleast 65, at least 70, at least 75, at least 80, at least 85, at least90, at least 95, or even at least 100 lbs of the PTFE; wherein themixture comprises no greater than 500, no greater than 300, no greaterthan 200, or even no greater than 150 lbs of PTFE; and/or wherein themixture comprises a range of at least 5 to no greater than 300 lbs ofPTFE, at least 40 to no greater than 200 lbs of PTFE, or even at least60 to no greater than 150 lbs of PTFE.

Item 119. The method of any one of the preceding items, wherein thearticle extruded from a single preform tube has a length of at least 60meters, at least 100 meters, at least 250 meters, at least 320 meters,at least 500 meters, at least 750 meters, at least 1,000 meters, atleast 1,250 meters, at least 1,500 meters, at least 1,750 meters, oreven at least 2,000 meters.

Item 120. The method of any one of the preceding items, wherein thearticle has a length of at least 60 meters, at least 100 meters, atleast 250 meters, at least 320 meters, at least 500 meters, at least 750meters, at least 1,000 meters, at least 1,250 meters, at least 1,500meters, at least 1,750 meters, or even at least 2,000 meters, andwherein the article is essentially joint free over a continuous lengthof 60 meters, 100 meters, 250 meters, 320 meters, 500 meters, 750meters, 1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even2,000 meters.

Item 121. The method of any one of the preceding items, whereinessentially all of the mixture that is loaded into the preform tube ismixed together in a single batch, and wherein the single batch comprisesat least 5, at least 7, at least 10, at least 12, at least 15, at least17, at least 20, at least 25, at least 30, at least 35, at least 40, atleast 45, at least 50, at least 55, at least 60, at least 65, at least70, at least 75, at least 80, at least 85, at least 90, at least 95, oreven at least 100 lbs of the PTFE; and/or wherein the single batchcomprises no greater than 500, no greater than 300, no greater than 200,or even no greater than 150 lbs of PTFE; and/or wherein the single batchcomprises a range of at least 5 to no greater than 300 lbs of PTFE, atleast 40 to no greater than 200 lbs of PTFE, or even at least 60 to nogreater than 150 lbs of PTFE.

Item 122. The method of any one of the preceding items, wherein thepreform tube has a length and a width, and wherein the length is greaterthan the width.

Item 123. The method of any one of the preceding items, wherein thepreform tube has a ratio of the length to the width of at least 3, atleast 5, at least 7, at least 10, or even at least 15.

Item 124. The method of any one of the preceding items, wherein thepreform tube has a generally cylindrical shape.

Item 125. The method of any one of the preceding items, wherein thepreform tube has a cross-sectional area of at least 10 in², at least 15in², at least 20 in², at least 25 in², or even at least 28 in²; whereinthe preform tube has a cross-sectional area of no greater than 100 in²,no greater than 50 in², or even no greater than 40 in²; and/or whereinthe preform tube has a cross-sectional area in a range of 10 in² to 50in², or even in a range of 20 in² to 40 in².

Item 126. The method of any one of the preceding items, wherein thearticle, has an average thickness of no greater than 1000 microns, nogreater than 500 microns, no greater than 250 microns, no greater than200 microns, no greater than 150 microns, no greater than 125 microns,no greater than 100 microns, no greater than 75 microns, or even nogreater than 60 microns; and/or an average thickness of at least 0.1microns, at least 1 micron, at least 5 microns, at least 10 microns, atleast 20 microns, at least 30 microns, or even at least 40 microns.

Item 127. The method of any one of the preceding items, wherein a ratioof the cross-sectional area of the preform tube to the narrowestcross-sectional area of the die (reduction ratio) is at least 50, atleast 60, at least 70, at least 80, at least 85, or even at least 90.

Item 128. The method of any one of the preceding items, wherein a ratioof the cross-sectional area of the preform tube to the narrowestcross-sectional area of the die (reduction ratio) is no greater than200, no greater than 160, no greater than 120, or even no greater than105.

Item 129. The method of any one of the preceding items, wherein activelycompacting the mixture from the first end begins before activelycompacting the mixture from the second end.

Item 130. The method of any one of the preceding items, wherein activelycompacting the mixture from the first end begins before activelycompacting the mixture from the second end, and wherein activelycompacting the mixture from the first end and actively compacting themixture from the second end occur, at least partly, concurrently.

Item 131. The method of any one of the preceding items, wherein acompaction force from the first and/or second end is no greater than 500psi, no greater than 400 psi, no greater than 350 psi, no greater than300 psi, no greater than 280 psi, no greater than 270 psi, no greaterthan 250 psi, no greater than 240 psi, no greater than 230 psi, nogreater than 220 psi, no greater than 210 psi, no greater than 200 psi,no greater than 190 psi, or even no greater than 180 psi.

Item 132. The method of any one of the preceding items, wherein acompaction force from the first and/or second end is no greater thanabout 280 psi, or even no greater than about 220 psi.

Item 133. The method of any one of the preceding items, wherein duringloading, compaction, translation, and/or extrusion, the first opening isdisposed at a higher elevation than the second opening.

Item 134. The method of any one of the preceding items, wherein duringloading, compaction, translation, and/or extrusion, the preform tube isin a generally vertical orientation.

Item 135. The method of any one of the preceding items, wherein activecompaction of the PTFE and lubricant from the first end begins beforeactive compaction of the PTFE and lubricant from the second end; oralternatively, wherein active compaction of the PTFE and lubricant fromthe second end begins before active compaction of the PTFE and lubricantfrom the first end.

Item 136. The method of any one of the preceding items, furthercomprising: calendering the article after extrusion, wherein the articlehas a first thickness after extrusion, the article has a secondthickness after calendering, and wherein the second thickness is lessthan the first thickness.

Item 137. The method of any one of the preceding items, furthercomprising: drying the article to drive off the lubricant.

Item 138. The method of any one of the preceding items, furthercomprising: winding the article to form a roll.

Item 139. The method of any one of the preceding items, furthercomprising: winding the article to form a roll; and cutting the ends ofthe roll.

Item 140. The method according to any one of the preceding items,wherein the PTFE comprises a PTFE homopolymer, a PTFE copolymer, orcombinations thereof.

Item 141. The method according to any one of the preceding items,wherein the article comprises a photosensitive material.

Item 142. The method according to any one of the preceding items,wherein the article comprises a photosensitive material, and wherein thephotosensitive material comprises a metal oxide.

Item 143. The method according to any one of the preceding items,wherein the article comprises a metal oxide, and wherein the metal oxidecomprises SnO₂, ZnO, AZO, TiO₂, CeO₂, Nb₂O₅, MoO₃, WO₃, V₂O₅, Cr₂O₃,Fe₂O₃, NiO, CuO, CdO, Tl₂O₃, or combinations thereof.

Item 144. The method according to any one of the preceding items,wherein the article comprises a photosensitive material in an amount ofat least about 0.1%, at least about 0.5%, or even at least about 1% byweight, based on the weight of the PTFE.

Item 145. The method according to any one of the preceding items,wherein the article comprises a photosensitive material in an amount ofno greater than 20%, no greater than 10%, or even no greater than about5% by weight, based on the weight of the PTFE.

Item 146. The method of any one of the preceding items, wherein the rollhas a cross-direction yield loss of no greater than 20%, no greater than18%, no greater than 16%, no greater than 14%, no greater than 12%, nogreater than 10%, no greater than 8%, or even no greater than 7%.

Item 147. The method of any one of the preceding items, wherein beforecutting, the roll has a Total Width Variation (TWV) of no greater than 3inches, no greater than 2 inches, no greater than 1.5 inch, or even nogreater than 1 inch.

Item 148. The method of any one of the preceding items, wherein beforecutting, the roll has a Total Width Variation (TWV) of at least 0.01inches, at least 0.1 inches, or even at least 0.5 inches.

Item 149. The method of any one of the preceding items, wherein beforecutting, the roll has a Total Width Variation (TWV) in a range of 0.01inches to 3 inches, 0.1 inches to 2 inches, or even 0.5 inches to 1.5inches.

Item 150. The method of any one of the preceding items, wherein thearticle is in the form of an article.

Item 151. The method of any one of the preceding items, wherein thearticle has a standard deviation of average thickness of no more than2.3 microns, no more than 2.2 microns, no more than 2.1 microns, no morethan 2.0 microns, no more than 1.9 microns, no more than 1.8 microns, nomore than 1.7 microns, no more than 1.6 microns, no more than 1.5microns, no more than 1.4 microns, no more than 1.3 microns, no morethan 1.2 microns, no more than 1.1 microns, no more than 1 micron, oreven no more than 0.9 microns over a continuous length of 60 meters, 100meters, 250 meters, 320 meters, 500 meters, 750 meters, 1,000 meters,1,250 meters, 1,500 meters, 1,750 meters, or even 2,000 meters.

Item 152. The method of any one of the preceding items, wherein thearticle has a standard deviation of average thickness of less than 2.3microns over a continuous length of 80 meters.

Item 153. The method of any one of the preceding items, wherein thearticle has a standard deviation of average thickness of less than 1.5microns over a continuous length of 320 meters.

Item 154. An article produced by the method of any one of the precedingitems.

Item 155. A PTFE tape produced by the method of any one of the precedingitems.

Item 156. A method for producing an article comprising PTFE, the methodcomprising: providing a preform tube having a first end and a secondend; loading a mixture comprising PTFE and lubricant into the preformtube; compacting the mixture within the preform tube; translating thepreform tube over a die, wherein the first end of the preform tube isnearer the die than the second end, wherein, during translation, thefirst end of the preform tube is open, and wherein substantially all ofthe compacted mixture is retained within the preform tube duringtranslation; and extruding the PTFE from the preform tube.

Item 157. A method for producing an article comprising PTFE, the methodcomprising: providing a first preform tube; loading a mixture comprisingPTFE into the first preform tube; translating the first preform tubeinto communication with a die and simultaneously, translating a secondpreform tube comprising PTFE out of communication with the die;extruding the mixture in the first preform tube.

Item 158. A method for producing an article comprising PTFE, the methodcomprising: providing a first preform tube; loading a mixture comprisingPTFE and lubricant into the first preform tube; translating the firstpreform tube into communication with a die; at least partly concurrentlyextruding the mixture in the first preform tube, and filling a secondpreform tube with a mixture comprising PTFE; at least partlyconcurrently translating the second preform tube into communication witha die and translating the first preform tube out of communication withthe die.

Item 159. The method of any one of the preceding items, furthercomprising applying a vacuum pressure to the second end of the preformtube during translation.

Item 160. The method of any one of the preceding items, furthercomprising applying a vacuum pressure to the second end of the preformtube during translation and releasing the vacuum pressure when thepreform tube is positioned over the die.

Item 161. The method of any one of the preceding items, furthercomprising applying a vacuum pressure to the second end of the preformtube during translation; abutting the first end of the preform tube intocommunication with the die, releasing the vacuum pressure when thepreform tube is positioned over the die while concurrently maintaining apressure release to allow the mixture to slide through the preform tube.

Item 162. The method of any one of the preceding items, furthercomprising compacting the mixture in the preform tube.

Item 163. The method of any one of the preceding items, furthercomprising compacting the mixture in the preform tube, and whereincompacting comprises actively compacting the mixture from a first endbefore actively compacting the mixture from the second end.

Item 164. The method of any one of the preceding items, furthercomprising compacting the mixture in the preform tube, and whereincompacting comprises actively compacting the mixture from the firstopening before actively compacting the mixture from the second end, andwherein actively compacting the mixture from the first end and activelycompacting the mixture from the second end occur, at least partly,concurrently.

Item 165. The method of any one of the preceding items, furthercomprising compacting the mixture in the preform tube, and wherein acompaction force from the first and/or second end is no greater thanabout 500 psi, no greater than about 400 psi, no greater than about 350psi, no greater than about 300 psi, no greater than about 280 psi, nogreater than about 270 psi, no greater than about 250 psi, no greaterthan about 240 psi, no greater than about 230 psi, no greater than about220 psi, no greater than about 210 psi, or even no greater than about200 psi.

Item 166. The method of any one of the preceding items, wherein acompaction force from the first and/or second end is no greater thanabout 280 psi, or even no greater than about 220 psi.

Item 167. The method of any one of the preceding items, wherein duringloading, compaction, translation, and/or extrusion, the first opening isdisposed at a higher elevation than the second opening.

Item 168. The method of any one of the preceding items, wherein duringloading, compaction, translation, and/or extrusion, the preform tube isin a generally vertical orientation.

Item 169. The method of any one of the preceding items, furthercomprising compacting the mixture in the preform tube, and whereincompacting comprises active compaction of the PTFE and lubricant fromthe first end beginning before active compaction of the PTFE andlubricant from the second end; or alternatively, wherein activecompaction of the PTFE and lubricant from the second end begins beforeactive compaction of the PTFE and lubricant from the first end.

Item 170. The method of any one of the preceding items, whereintranslation includes rotating a first preform tube and a second preformtube about a central axis, and wherein the first end of the first andsecond preform tubes remains at a lower elevation than the second end ofthe first and second preform tubes respectively throughout rotation.

Item 171. The method of any one of the preceding items, furthercomprising: calendering the article after extrusion, wherein the articlehas a first thickness after extrusion, the article has a secondthickness after calendering, and wherein the second thickness is lessthan the first thickness.

Item 172. The method of any one of the preceding items, furthercomprising: drying the article to drive off the lubricant.

Item 173. The method of any one of the preceding items, furthercomprising: winding the article to form a roll.

Item 174. The method of any one of the preceding items, furthercomprising: winding the article to form a roll; and cutting the ends ofthe roll.

Item 175. The method according to any one of the preceding items,wherein the PTFE comprises a PTFE homopolymer, a PTFE copolymer, orcombinations thereof.

Item 176. The method according to any one of the preceding items,wherein the article comprises a photosensitive material.

Item 177. The method according to any one of the preceding items,wherein the article comprises a photosensitive material, and wherein thephotosensitive material comprises a metal oxide.

Item 178. The method according to any one of the preceding items,wherein the article comprises a metal oxide, and wherein the metal oxidecomprises SnO₂, ZnO, AZO, TiO₂, CeO₂, Nb₂O₅, MoO₃, WO₃, V₂O₅, Cr₂O₃,Fe₂O₃, NiO, CuO, CdO, Tl₂O₃, or combinations thereof.

Item 179. The method according to any one of the preceding items,wherein the article comprises a photosensitive material in an amount ofat least about 0.1%, at least about 0.5%, or even at least about 1% byweight, based on the weight of the PTFE.

Item 180. The method according to any one of the preceding items,wherein the article comprises a photosensitive material in an amount ofno greater than 20%, no greater than 10%, or even no greater than about5% by weight, based on the weight of the PTFE.

Item 181. The method of any one of the preceding items, wherein thearticle has a standard deviation of average thickness of no more than2.3 microns, no more than 2.2 microns, no more than 2.1 microns, no morethan 2.0 microns, no more than 1.9 microns, no more than 1.8 microns, nomore than 1.7 microns, no more than 1.6 microns, no more than 1.5microns, no more than 1.4 microns, no more than 1.3 microns, no morethan 1.2 microns, no more than 1.1 microns, no more than 1 micron, oreven no more than 0.9 microns over a continuous length of 60 meters, 100meters, 250 meters, 320 meters, 500 meters, 750 meters, 1,000 meters,1,250 meters, 1,500 meters, 1,750 meters, or even 2,000 meters.

Item 182. The method of any one of the preceding items, wherein thearticle has a standard deviation of average thickness of less than 2.3microns over a continuous length of 80 meters.

Item 183. The method of any one of the preceding items, wherein thearticle has a standard deviation of average thickness of less than 1.5microns over a continuous length of 320 meters.

Item 184. An article produced by the method of any one of the precedingitems.

Item 185. A PTFE tape produced by the method of any one of the precedingitems.

Item 186. The article according to any one of the preceding items,wherein the PTFE article has a maximum low spot thickness of less than30%, less than 25%, less than 20%, no greater than 18%, no greater than16%, no greater than 14%, no greater than 12%, no greater than 10%, nogreater than 8%, no greater than 6%, or even no greater than 5%.

Item 187. The article according to any one of the preceding items,wherein the PTFE article has a maximum low spot thickness of less than20%, no greater than 10%, or even no greater than 5%.

Item 188. The article according to any one of the preceding items,wherein the PTFE article has a maximum low spot thickness of less than30%, less than 25%, less than 20%, no greater than 18%, no greater than16%, no greater than 14%, no greater than 12%, no greater than 10%, nogreater than 8%, no greater than 6%, or even no greater than 5% over acontinuous length of 60 meters, 100 meters, 250 meters, 320 meters, 500meters, 750 meters, 1,000 meters, 1,250 meters, 1,500 meters, 1,750meters, or even 2,000 meters.

Item 189. The article according to any one of the preceding items,wherein the PTFE article has a maximum low spot thickness of less than30%, less than 25%, less than 20%, no greater than 18%, no greater than16%, no greater than 14%, no greater than 12%, no greater than 10%, nogreater than 8%, no greater than 6%, or even no greater than 5% over acontinuous length of 100 meters, and a mean average thickness of lessthan 250 microns, less than 80 microns, or even less than 50 microns.

Item 190. The expanded article of any one of the preceding items,wherein the expanded PTFE article has a maximum low spot thickness ofless than 30%, less than 25%, less than 20%, no greater than 18%, nogreater than 16%, no greater than 14%, no greater than 12%, no greaterthan 10%, no greater than 8%, no greater than 6%, or even no greaterthan 5%.

Item 191. The expanded article of any one of the preceding items,wherein the expanded PTFE article has a maximum low spot thickness ofless than 20%, no greater than 10%, or even no greater than 5%.

Item 192. The expanded article of any one of the preceding items,wherein the expanded PTFE article has a maximum low spot thickness ofless than 30%, less than 25%, less than 20%, no greater than 18%, nogreater than 16%, no greater than 14%, no greater than 12%, no greaterthan 10%, no greater than 8%, no greater than 6%, or even no greaterthan 5% over a continuous length of 60 meters, 100 meters, 250 meters,320 meters, 500 meters, 750 meters, 1,000 meters, 1,250 meters, 1,500meters, 1,750 meters, or even 2,000 meters.

Item 193. The expanded article of any one of the preceding items,wherein the expanded PTFE article has a maximum low spot thickness ofless than 30%, less than 25%, less than 20%, no greater than 18%, nogreater than 16%, no greater than 14%, no greater than 12%, no greaterthan 10%, no greater than 8%, no greater than 6%, or even no greaterthan 5% over a continuous length of 100 meters, and a mean averagethickness of less than 250 microns, less than 80 microns, or even lessthan 50 microns.

Item 194. The method of any one of the preceding items, wherein the PTFEarticle has a maximum low spot thickness of less than 30%, less than25%, less than 20%, no greater than 18%, no greater than 16%, no greaterthan 14%, no greater than 12%, no greater than 10%, no greater than 8%,no greater than 6%, or even no greater than 5%.

Item 195. The method of any one of the preceding items, wherein the PTFEarticle has a maximum low spot thickness of less than 20%, no greaterthan 10%, or even no greater than 5%.

Item 196. The method of any one of the preceding items, wherein the PTFEarticle has a maximum low spot thickness of less than 30%, less than25%, less than 20%, no greater than 18%, no greater than 16%, no greaterthan 14%, no greater than 12%, no greater than 10%, no greater than 8%,no greater than 6%, or even no greater than 5% over a continuous lengthof 60 meters, 100 meters, 250 meters, 320 meters, 500 meters, 750meters, 1,000 meters, 1,250 meters, 1,500 meters, 1,750 meters, or even2,000 meters.

Item 197. The method of any one of the preceding items, wherein the PTFEarticle has a maximum low spot thickness of less than 30%, less than25%, less than 20%, no greater than 18%, no greater than 16%, no greaterthan 14%, no greater than 12%, no greater than 10%, no greater than 8%,no greater than 6%, or even no greater than 5% over a continuous lengthof 100 meters, and a mean average thickness of less than 250 microns,less than 80 microns, or even less than 50 microns.

Item 198. An article, an expanded article, a cable or wire assembly, ora method of any one of the preceding items, wherein instead of PTFE, thearticle, expanded article, a cable or wire assembly contains anon-meltprocessable polymer.

Note that not all of the activities described above in the generaldescription or the examples are required, that a portion of a specificactivity may not be required, and that one or more further activitiesmay be performed in addition to those described. Still further, theorder in which activities are listed is not necessarily the order inwhich they are performed.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any feature(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeature of any or all the claims.

The specification and illustrations of the embodiments described hereinare intended to provide a general understanding of the structure of thevarious embodiments. The specification and illustrations are notintended to serve as an exhaustive and comprehensive description of allof the elements and features of apparatus and systems that use thestructures or methods described herein. Separate embodiments may also beprovided in combination in a single embodiment, and conversely, variousfeatures that are, for brevity, described in the context of a singleembodiment, may also be provided separately or in any subcombination.Further, reference to values stated in ranges includes each and everyvalue within that range. Many other embodiments may be apparent toskilled artisans only after reading this specification. Otherembodiments may be used and derived from the disclosure, such that astructural substitution, logical substitution, or another change may bemade without departing from the scope of the disclosure. Accordingly,the disclosure is to be regarded as illustrative rather thanrestrictive.

What is claimed is:
 1. An article comprising polytetrafluoroethylene(PTFE), the article having a continuous length of at least 500 meters,wherein the article has a mean average thickness of less than 250microns, and wherein the article is essentially free of artifacts ofpaste extrusion between successive preforms over a continuous length of500 meters and wherein the article has a standard deviation of meanaverage thickness of no more than 1.6 microns.
 2. The article accordingto claim 1, wherein the article has a total thickness variation (TTV) ofless than 20 microns over a continuous length of 500 meters.
 3. Thearticle according to claim 1, wherein the article has a % thicknessvariation of less than 10% over a continuous length of 500 meters. 4.The article according to claim 1, wherein the article has a maximum lowspot thickness of less than 10% over a continuous length of 500 meters.5. The article according to claim 1, wherein the article has a standarddeviation of the mean average thickness of no more than 1.3 microns. 6.The article according to claim 1, wherein the article a. has a totalthickness variation (TTV) of less than 20 microns over a continuouslength of 500 meters; b. has a % thickness variation of less than 20%over a continuous length of 500 meters; and c. has a maximum low spotthickness of less than 20% over a continuous length of 500 meters. 7.The article according to claim 1, wherein the article has a continuouslength of at least 1000 meters, and wherein the recited characteristicsapply over a continuous length of 1000 meters.
 8. The article accordingto claim 1, wherein the article has a continuous length of at least 2000meters, and wherein the recited characteristics apply over a continuouslength of 2000 meters.
 9. The article according to claim 1, wherein thearticle has a mean average thickness of no greater than 150 microns. 10.The article according to claim 1, wherein the article has an averageGurley permeability of at least 70 seconds over a continuous length of500 meters.
 11. The article according to any claim 1, wherein thearticle is formed from a paste extrusion process in which the article ispaste extruded from a single preform containing at least 30 lbs of PTFE.12. The article according to claim 1, wherein the article is formed froma paste extrusion process in which: a. the article is paste extrudedfrom a single preform containing at least 30 lbs of PTFE; b. wherein araw material mixture containing at least 30 lbs of PTFE that is used toform a single preform is mixed together in a single batch; and/or c.wherein a single preform is formed from compression in a preform tube ata compaction pressure of less 300 psi.
 13. The article according toclaim 1, wherein the article is unsintered.
 14. The article according toclaim 13, wherein the article comprises expanded PTFE.
 15. The articleaccording to claim 1, wherein the article further comprises atransmission member, and an insulation member, and wherein theinsulation member is wrapped around the transmission member, and whereinthe article is contained in the insulation member.
 16. The articleaccording to claim 1, wherein the article consists essentially of PTFE.17. A cable or wire assembly comprising: a transmission member; and aninsulation member, wherein the insulation member is wrapped around thetransmission member, and wherein the insulation member comprises a layerconsisting essentially of PTFE, wherein the layer has an unwoundcontinuous length of at least 500 meters, wherein the layer has a meanaverage thickness of less than 250 microns, and wherein the layer isessentially free of artifacts of paste extrusion between successivepreforms over a continuous unwound length of 500 meters and wherein thelayer consisting essentially of PTFE has a standard deviation of meanaverage thickness of no more than 1.6 microns.